• Announcements

    • Zapata

      Abbreviated rules   07/28/2017

      Underdawg did an excellent job of explaining the rules.  Here's the simplified version: Don't insinuate Pedo.  Warning and or timeout for a first offense.  PermaFlick for any subsequent offenses Don't out members.  See above for penalties.  Caveat:  if you have ever used your own real name or personal information here on the forums since, like, ever - it doesn't count and you are fair game. If you see spam posts, report it to the mods.  We do not hang out in every thread 24/7 If you see any of the above, report it to the mods by hitting the Report button in the offending post.   We do not take action for foul language, off-subject content, or abusive behavior unless it escalates to persistent stalking.  There may be times that we might warn someone or flick someone for something particularly egregious.  There is no standard, we will know it when we see it.  If you continually report things that do not fall into rules #1 or 2 above, you may very well get a timeout yourself for annoying the Mods with repeated whining.  Use your best judgement. Warnings, timeouts, suspensions and flicks are arbitrary and capricious.  Deal with it.  Welcome to anarchy.   If you are a newbie, there are unwritten rules to adhere to.  They will be explained to you soon enough.  

Archived

This topic is now archived and is closed to further replies.

Ajax

Pump It!

Recommended Posts

I've observed at the dock, that if the wind is strong enough, and blowing from the right direction, my mast pumps.

 

Boat characteristic?

Rigging out of tune?

Something else?

Share this post


Link to post
Share on other sites

Hi Ajax, old school straight mast, single spreader with no for/aft lines at mid span? Do you have a topping lift you can run to the stem and tighten?

Share this post


Link to post
Share on other sites

Hi Ajax, old school straight mast, single spreader with no for/aft lines at mid span? Do you have a topping lift you can run to the stem and tighten?

 

+1. A spin pole topping lift can preload the mast and dampen pumping.

Share this post


Link to post
Share on other sites

I've observed at the dock, that if the wind is strong enough, and blowing from the right direction, my mast pumps.

 

Boat characteristic?

Rigging out of tune?

Something else?

 

The mast on our 29 used to pump like crazy with wind from the right (wrong) direction. I retuned the rig several times to little effect, but the pumping didn't go mostly away until I pulled the rig and started over. Putting the babystay on hard helped.

 

Our 35 hardly ever pumps, but the port cap shroud does sing something ferocious at times. Sailing along in a breeze on port tack, we're sitting in the cockpit and there's an eerie hum. It took me a while to figure it out. It's very odd and I don't know why just the port shroud. I have a Flight of the Valkyries sensation when it's really howling.

Share this post


Link to post
Share on other sites

I once had a boat with a mast that pumped under sail in a chop. It pumped so much that I lost the mast due to the spreader root casting fatiguing. We replaced the mast with a wider fore and aft section which helped.

 

Observe your mast under sail. The main can have a stabilizing effect on the mast. If it pumps with the main up you will need to do some re-tuning. I have not heard of Pearson 30s having particular problems with their masts but it might be worth talking to other owners. Meanwhile, as the others have said, lead your topping lift forward and tighten it up when the boat is docked to prevent movement.

Share this post


Link to post
Share on other sites

On my O'Day I used to run the spin pole topping lift to the stem and crank a turn or two on the halyard winch to induce some bend. I only did this because I was a live aboard and needed the quiet, otherwise probably would have let it be. You can also induce some bend by running the main halyard to somewhere aft, but then the halyard may start to buzz...

Share this post


Link to post
Share on other sites

Ajax,

 

This is pretty common amongst old-school straight rigs with the shrouds in-line with the rig. I'm guessing here, but I think you might not have fore and aft lower shrouds, but only have one shroud going to the root of the spreader that is mounted almost exactly where the upper shroud is on deck. If you do have both forward and after lowers, insure that they both have at least a little tension on them when you're at the dock. Again, if you do have both types of lower shrouds you can sometime stop this (without tightening the lowers) by running a line about 7' above the deck from one after lower to the other. Tie it tightly, pinching the after lowers together, to tighten them and keep the middle of the mast still.

 

In the event that you've only got one set of lowers, which I'm guessing is the case, then you can take the Spin halyard and run it under the spreader and back aft to the rail or some strong point. Then, haul in on the spin halyard and it will pull the center of the mast aft. The halyard will chafe a little on the spreader, so you may want to install something more permanent once you figure out if this works. If the Spin halyard under the spreader trick works, then there are a number of options. You can use the spin pole lift, a flag halyard from the spreader, or a fixed line that runs from the root of the spreader and simply tie it off firmly either fore or aft with enough load on it to stop the pumping. You want a line that doesn't stretch, stretchy line can actually make the situation worse as it's a spring in the system.

 

BTW, if your rig pumps while at the dock it is probably pumping big time in a heavy sea unless the mainsail is holding it still. Take a good look and consider this if you're ever sailing without the main up. Lots of folks sail with the main down and only a storm jib in really heavy conditions. If your rig pumps at the dock, it will probably pump like a damn fire truck in a heavy sea with only a jib up. This is obviously a "bad thing" as the rig will come down at some point from this if the pumping is large enough. For this reason, a lot of single spreader rigs from the '60s have running back stays, not to hold the rig up "normally" but to keep it from pumping in a big sea.

 

Best,

 

BV

Share this post


Link to post
Share on other sites

Sorry guys, but I do have fore/aft lower shrouds. I have not observed any pumping while at sea, but I never sail without the main, (at least, I haven't yet).

 

They do have a little tension at the dock, but I'll tell you that the leeward lowers get pretty slack when sailing in even a moderate breeze (on both tacks). In a light breeze, not so much. It sounds like perhaps I should take a turn on my lowers, if that doesn't help, maybe I should "start over", like Ish did.

 

I have not tuned the rig, it's just as it was on the day I bought it last August.

Share this post


Link to post
Share on other sites

Tune it! Google Selden mast and look ar thier tuning guide. Very clear and easy to follow. 20% on the cap shrouds and enough on the forward lowers to induce a slight bend. A bit less on the aft lowers for starters.

Share this post


Link to post
Share on other sites

You need a tighter rig tune across the board, & prebend. If your lee shrouds get floppy slack going upwind, the whole rig is too loose. Basic cruising tensions should have the lee shrouds loose, but not moving on their own. A tighter rig will also let you put in some prebend, which should stop the pumping.

Basic tension guide for a single spreader spar with double lowers: overall tension tight enough that lee shrouds stay firm. If you call the tension on the uppers a "3", than fore lowers should be "2", & aft lowers "1-1 1/2". Spar must be straight sideways & centered over boat. Fore/aft the spar should have 1/2 mast dia bend forwards.

Get out a 50' steel tape, hoist it to the masthead, & measure side to side. Cast a critical eye on what you measure to, many chainplates are not evenly installed. The turn of the hull/deck joint can be more accurate. Center the masthead using the uppers. Next slack off the aft lowers and pull the spar straight amidships with the fore lowers. Put enuff tension on the fores to pull the middle of the spar forward about 1 spar diameter. Now tension the aft lowers to reduce prebend to 1/2 a dia. Go sailing upwind & sight up the mainsail track for bends. Take them out by adjusting the lee shrouds & then tacking to see if adjustment works. Keep both sides even on turn adjustment - if adjustment works, do same to the now lee shrouds, tack & verify. Best is to sneak up slowly on turns until you have a real feel on how responsive your spar is. Final tune should have equal tension on all shroud pairs - if not, there's something else going on that you need to track down.

Share this post


Link to post
Share on other sites

You need a tighter rig tune across the board, & prebend. If your lee shrouds get floppy slack going upwind, the whole rig is too loose. Basic cruising tensions should have the lee shrouds loose, but not moving on their own. A tighter rig will also let you put in some prebend, which should stop the pumping.

Basic tension guide for a single spreader spar with double lowers: overall tension tight enough that lee shrouds stay firm. If you call the tension on the uppers a "3", than fore lowers should be "2", & aft lowers "1-1 1/2". Spar must be straight sideways & centered over boat. Fore/aft the spar should have 1/2 mast dia bend forwards.

Get out a 50' steel tape, hoist it to the masthead, & measure side to side. Cast a critical eye on what you measure to, many chainplates are not evenly installed. The turn of the hull/deck joint can be more accurate. Center the masthead using the uppers. Next slack off the aft lowers and pull the spar straight amidships with the fore lowers. Put enuff tension on the fores to pull the middle of the spar forward about 1 spar diameter. Now tension the aft lowers to reduce prebend to 1/2 a dia. Go sailing upwind & sight up the mainsail track for bends. Take them out by adjusting the lee shrouds & then tacking to see if adjustment works. Keep both sides even on turn adjustment - if adjustment works, do same to the now lee shrouds, tack & verify. Best is to sneak up slowly on turns until you have a real feel on how responsive your spar is. Final tune should have equal tension on all shroud pairs - if not, there's something else going on that you need to track down.

 

Also keep track of what you have done so you have a baseline for further performance tuning and for re-tuning the rig if you have to take the mast down.

Share this post


Link to post
Share on other sites

We have fore and aft D1's, inner forestay, runners and checks........and it pumps. Sometimes it sings so loud it sounds like a welder is running below.

 

Sometimes, rigs pump........

Share this post


Link to post
Share on other sites

We have fore and aft D1's, inner forestay, runners and checks........and it pumps. Sometimes it sings so loud it sounds like a welder is running below.

 

Sometimes, rigs pump........

 

I'm no rig expert Joli but with that setup I am surprised the mast still pumps. Are you happy its all tight enough?

Share this post


Link to post
Share on other sites

Ajax, shoot me a pm or email if you want to re-tune the rig. My tension guage won't work (you have larger wire) but we can get it close with tape measure and some time. We can do a base at the dock, then final tune out in the bay. Need semi consistant conditions.

Share this post


Link to post
Share on other sites

Ajax, shoot me a pm or email if you want to re-tune the rig. My tension guage won't work (you have larger wire) but we can get it close with tape measure and some time. We can do a base at the dock, then final tune out in the bay. Need semi consistant conditions.

 

The Selden tape rule method for tensioning your shrouds works great. At Selden rig tuning you can download their tuning guide. It's a PDF file.

Share this post


Link to post
Share on other sites

Ajax, shoot me a pm or email if you want to re-tune the rig. My tension guage won't work (you have larger wire) but we can get it close with tape measure and some time. We can do a base at the dock, then final tune out in the bay. Need semi consistant conditions.

 

The Selden tape rule method for tensioning your shrouds works great. At Selden rig tuning you can download their tuning guide. It's a PDF file.

 

Thanks, between the tuning guide and a visit from Merit25, I should be able to improve the tune greatly.

 

I do know this: The mast tip does not fall off to leeward when I sail (thank God) or I probably would have lost the rig already. rolleyes.gif

Share this post


Link to post
Share on other sites

Hey Paps. We jack it to 30,000 lbs on the caps which is what the sparmaker recomends for cruising, racing is 40,000 lbs but they do not recomend letting the boat sit with that pressure. We use the hydraulic gage to measure the load when we jack the rig. I haven't heard of gages going bad but I'll ask some of my hydraulic buddies, maybe? Upwind, top of the 1 (27 over the deck) we don't fall off more then 6 inches when set too cruising tensions, so it seems like we are setting the caps hard enough. It only pumps at the dock, I've never felt it sailing, and no matter what I try it will still move during some wind speeds and directions at the dock. It's a big rig, I've always assumed it was panel movement between the spreaders. But maybe, I'll do some more checking.......thanks.

 

IMG_0482.jpg

 

 

 

We have fore and aft D1's, inner forestay, runners and checks........and it pumps. Sometimes it sings so loud it sounds like a welder is running below.

 

Sometimes, rigs pump........

 

I'm no rig expert Joli but with that setup I am surprised the mast still pumps. Are you happy its all tight enough?

Share this post


Link to post
Share on other sites

Hey Paps. We jack it to 30,000 lbs on the caps which is what the sparmaker recomends for cruising, racing is 40,000 lbs but they do not recomend letting the boat sit with that pressure. We use the hydraulic gage to measure the load when we jack the rig. I haven't heard of gages going bad but I'll ask some of my hydraulic buddies, maybe? Upwind, top of the 1 (27 over the deck) we don't fall off more then 6 inches when set too cruising tensions, so it seems like we are setting the caps hard enough. It only pumps at the dock, I've never felt it sailing, and no matter what I try it will still move during some wind speeds and directions at the dock. It's a big rig, I've always assumed it was panel movement between the spreaders. But maybe, I'll do some more checking.......thanks.

 

IMG_0482.jpg

 

 

 

We have fore and aft D1's, inner forestay, runners and checks........and it pumps. Sometimes it sings so loud it sounds like a welder is running below.

 

Sometimes, rigs pump........

 

I'm no rig expert Joli but with that setup I am surprised the mast still pumps. Are you happy its all tight enough?

 

OK I didn't get that you meant only at the dock. Certainly the cap loads are substantial, I was just surprised the Fore and Aft D1's plus inner forestay, runners and checks weren't keeping things steady? Do you have much pre bend at the dock?

Share this post


Link to post
Share on other sites

Hey Paps, maybe half a section, no more then that. The partners are custom so I haven't tried more prebend through them. The innner forestay is 3/8" on a hyfield, not sure how loaded I want that but maybe you are right and I'll load those and the forward D1's some more. I'll let you know this summer.

Share this post


Link to post
Share on other sites

Had the problem on my last boat depending on the wind speed and angle (at dock only). I messed around with various rig tension combo's with very little difference. Mentioned it to a rigger I knew and he said frequently it has to do with mast shape and wind vorticies on the trailing edge. Suggested I do something to break the symmetry of the mast to lessen the affect. He suggested I take a couple of halyards, twist them together and wrap the mast several times on the way down. It actually helped a bit. Later another guy I ran into suggested that I could have hauled a fender into the rigging on a halyard (with a downhaul of course) and wrap the mast similarly with the fender tight against the mast. I had moved on to another boat by then so I never got a chance to try that one.

Share this post


Link to post
Share on other sites

A lot of comments about cranking on the caps to induce pre bend. I think this boat will have inline spreaders, so cranking the caps will not induce any bend (not in the rig anyway...). You do obviously need enought tension to stop the whole thing flopping about.

 

You need something pulling forward or aft around mid point, like the topping life suggestion. You could also run the main halyard under the spreader and forward but it might chafe.

 

Other wise tie a warp around the mast and use a halyard to pull it up to the spreaders, then use that to pull the middle of the mast forward.

 

I’ve seen mast pumps while sailing, in particular while sailing down wind in a sea with no main up. I’ve never seen the problem at the dock, sounds odd.

Share this post


Link to post
Share on other sites

We're an in line rig so tension on the caps does nothing for prebend, we set the caps hard enough to keep the top from falling off. With our inline rig we have five locations for adding prebend, from the bottom up: mast butt, chocks at the partners, forward D1's, intermediate headstays and the masthead crane.

 

When we set the rig we key the butt, crank the mast forward at deck level so we're preloaded at partners, we then set the cap tension, then tune from the D1's up. The panel between the first and third spreader has no for and aft support other then preload (the D1's terminate at the base of the first spreader and the inner forestay terminates at the base of the third spreader). That's a ~45 foot section with no fore and aft support other then prebend. We assume that's where the rig pumps. Again it only happens at the dock, never when sailing or at anchor. We figure it's harmonics of some sort when the wind is a certain speed and angle. Fooling around with backstay pressures, and D1's and inner forestay tensions doesn't seem to do much so..... fuctifwekno?

 

Options?

Share this post


Link to post
Share on other sites

Is the rig deck stepped or keel stepped? If it is keel stepped you can add prebend by moving the butt aft and chocking forward at the partners. Use a line around the mast at deck level, pull it forward and chock behind the mast. This will give you some prebend, then set your forward D1's with more tension then your aft D1's. Does the P30 have a masthead crane extensions aft?

 

2.jpg

 

If it does, then when you tension the rig using your backstay then rig will bow more. Without the aft extension you're only relying on what you pick up from the D1.

 

Good luck.

 

I've observed at the dock, that if the wind is strong enough, and blowing from the right direction, my mast pumps.

 

Boat characteristic?

Rigging out of tune?

Something else?

Share this post


Link to post
Share on other sites

Joli - my response was aimed at the OP problem. Do you say you have checks and an intermediate head stay?

 

If it's still wobbling with a decent tension on the intermediate forestay and topmast backstay and a little tension on the checks then I'm stumped as well. Your set up sounds pretty sensible to me.

Share this post


Link to post
Share on other sites

You and me both Bloke.... Ajax's situation should be fixable by retuning unless he is getting some funky harmonics.

 

Joli - my response was aimed at the OP problem. Do you say you have checks and an intermediate head stay?

 

If it's still wobbling with a decent tension on the intermediate forestay and topmast backstay and a little tension on the checks then I'm stumped as well. Your set up sounds pretty sensible to me.

Share this post


Link to post
Share on other sites

FWIW, most mast pumping at the dock is caused by the Van Karman Vortex street phenomenon. Explanation here Von Karman Vortex. There is a pretty good animation too. Explains why you always see spiral flutes on cylindrical structures like those in a refinery. My mast pumps at certain wind angles too. Changing rig tension will change the resonant frequency at which the mast pumps and may fix the problem.

Share this post


Link to post
Share on other sites

For whatever it's worth I thought I had mast pumping going on but it was really just a harmonic from some halyards that was causing a "pumping". I'm sure you guys would have figured that out by now but as I was trying to identify the super complicated answer it was something as simple as a line.

Share this post


Link to post
Share on other sites

Ajax, it just doesn't appear to be falling off at the top because the lowers are so loose that the mast tube is falling into column. :P Which is better than the uppers too tight and the lowers too loose & the rig buckling in the middle.

 

Loosen everything to hand tight..get it straight side to side and fore & aft, (merit25 will hook you up there, but we could also chat about it over the phone) and then tighten up & tune a bit. the first time I took my new rig sailing, every time we tacked, I added a turn or two on the slack side (counting the same on both sides) & two seasons later it is time to do it again after everything has settled and stretched out (I also did a lot of bulkhead work). Our old boats move a bit, so you have to be patient with them. I am surprised my rig did not fall down the first season after I learned more about how bad my bulkheads were. :unsure:

 

Don't forget to 'pin' the rig so the turnbuckles won't loosen up. On our old boats you should pin both top & bottom of the threads. (I took cotter pins, snipped them to length, & sewed them to velcro wrap, but you can also get some from APS pre-made.) - another common idea is to use ring dings and tape them so they don't catch toes, gear & sails, but they are not real easy to adjust..this more applies to race boats when you are adjusting the rig in between races as the conditions change.

Share this post


Link to post
Share on other sites

I tune my aft lowers loose but not moving freely at 20 degrees of heel, forward lowers a little tighter than the aft ones but you really can't bend that mast.

 

My P26 used to pump until you would think it was going to have an orgasm but the 30 was never that bad. I don't know if it's just coincidence but since I've had the adjustable backstay the 30 doesn't hump and pump.

Share this post


Link to post
Share on other sites

I tune my aft lowers loose but not moving freely at 20 degrees of heel, forward lowers a little tighter than the aft ones but you really can't bend that mast.

 

My P26 used to pump until you would think it was going to have an orgasm but the 30 was never that bad. I don't know if it's just coincidence but since I've had the adjustable backstay the 30 doesn't hump and pump.

 

I had the adjustable backstay, the adjustable babystay, and all the other shit on the 29 and it still humped the boat in a big wind. In 30 knots from the wrong direction (pick any) the whole boat would shake like a wet dog. I think it was too well tuned, the shrouds were in tune with the fore and backstay, everything had a bottom harmonic. Pulling the rig and starting over with a determination to avoid the harmonic was the only fix.Probably doing a maypole dance around the mast would have sufficed, except I couldn't find enough Morris dancers.

Share this post


Link to post
Share on other sites

Did anyone read his post, his mast pumps when at the dock, and only under certain conditions, NOT WHEN SAILING!!! It is just common Van Karmen vortex, that is all. Just change the airfoil shape by wrapping halyards around it or by any other means and it will stop. No need to re rig or anything else. take a look at modern car antennas, the spiral wrap is there for a reason.

 

Pal

Share this post


Link to post
Share on other sites

Did anyone read his post, his mast pumps when at the dock, and only under certain conditions, NOT WHEN SAILING!!! It is just common Van Karmen vortex, that is all. Just change the airfoil shape by wrapping halyards around it or by any other means and it will stop. No need to re rig or anything else. take a look at modern car antennas, the spiral wrap is there for a reason.

 

Pal

 

I don't know about that Pal, our mast used to pump something fierce when it was windy at anchor, and nothing I did to it (including hauling the dinghy halfway up the mast) fixed it. Sometimes it seemed the boat was going to shake itself to pieces. The only thing that worked was dragging the stick out and starting over, although I don't know why detaching the rigging and retuning wouldn't have worked the same...

Share this post


Link to post
Share on other sites

Pal, good point, and in theory I agree with you, but I think that the pumping inherently means that perhaps the rig is too loose for general sailing conditions if it is pumping at the dock.

 

On the Tartan 3000 I race on (keel stepped) we removed the babystay since it was a pain to tack the jib around. Once we noticed that the rig liked to pump upwind, to counteract this problem (no babstay to prevent pumping) we jammed some wedges in at the aft edge of the partners to induce some prebend to keep the rig from pumping. it helped a lot..the Tartan has inline D1's & D2's, so the wedging was necessary. If it was my boat, I might have induced even a little more pre-bend than we had, but then I made the MFO drive while I looked up at the rig....this is a much different issue on a deck stepped mast...I think you gotta stabilize Ajax's rig with the lowers.

Share this post


Link to post
Share on other sites

Ajax,

 

Next time you see this happening, pull you halyards away from the mast and see what happens...

 

Halyards are internal, so there's nothing to pull away.

Share this post


Link to post
Share on other sites

Ajax,

 

Next time you see this happening, pull you halyards away from the mast and see what happens...

 

Halyards are internal, so there's nothing to pull away.

 

That's guna be upsetting next time you try to go sailing.

Share this post


Link to post
Share on other sites

Are you sure about that? Sorry wine talking, I'll go now. Promise.

 

The halyards are inside the mast, and only pop out for a few feet to go to their cleats. Oh...I see what you're saying. The rest of both halyards are nowhere near the mast. The jib halyard is clipped to the pulpit and the main halyard is clipped to the toe rail. D'oh! :rolleyes:

Share this post


Link to post
Share on other sites

Ajax, A little bow in the stick should eliminate the pumping..even on a deck stepped rig..however, the whole rig may be too loose. Pull a little (like one or two turns) on the forward lowers and ease of the aft lowers an equal amount. Has Merit25 come to the boat to help you out yet?

Share this post


Link to post
Share on other sites

Are you sure about that? Sorry wine talking, I'll go now. Promise.

 

The halyards are inside the mast, and only pop out for a few feet to go to their cleats. Oh...I see what you're saying. The rest of both halyards are nowhere near the mast. The jib halyard is clipped to the pulpit and the main halyard is clipped to the toe rail. D'oh! :rolleyes:

 

Gilda Radner voice - "Never mind..."

Share this post


Link to post
Share on other sites

Ajax, A little bow in the stick should eliminate the pumping..even on a deck stepped rig..however, the whole rig may be too loose. Pull a little (like one or two turns) on the forward lowers and ease of the aft lowers an equal amount. Has Merit25 come to the boat to help you out yet?

 

Nah, haven't had the time yet. I'll try what you're saying, but I'm not sure I even need to ease the aft lowers, because those were the ones that were really sloppy on the leeward side. The forward lowers were just a bit soft.

Share this post


Link to post
Share on other sites

my forward lowers really load up on the windward side under load..the aft lowers are always sloppy.

 

Sounds like you may need to unload the rig and let things settle and start from scratch. Any tuning numbers from your fellow P-30 owners for things like starting headstay length, etc?

Share this post


Link to post
Share on other sites

Update:

 

Have you guys ever heard of anyone unloading the rigging when putting a boat into storage or on the hard? De-tensioning, I mean, but leaving the rigging still attached?

 

Blowing 20 kts, I took the boat out and sailed with no main, under a #2 jib. Upwind, the stick was nice and straight, so I feel good about the cap/upper shrouds. When the wind was on either of the aft quarters, the rig pumped. I could see it and feel it. I came up to a beam reach and it would stop. This only happened when I got into a lighter breeze, in the lee of a shore. In harder breeze, it wouldn't do it. At any rate, when I could see the pumping, it looks like the forward lowers are simply too loose. This was the first time I'd observed mast pumping under sail.

 

Someone earlier in the thread recommended that I tighten the forward lowers, so I will.

Share this post


Link to post
Share on other sites

Update:

 

Blowing 20 kts, I took the boat out and sailed with no main, under a #2 jib. Upwind, the stick was nice and straight, so I feel good about the cap/upper shrouds. When the wind was on either of the aft quarters, the rig pumped. I could see it and feel it. I came up to a beam reach and it would stop. This only happened when I got into a lighter breeze, in the lee of a shore. In harder breeze, it wouldn't do it. At any rate, when I could see the pumping, it looks like the forward lowers are simply too loose. This was the first time I'd observed mast pumping under sail.

 

Someone earlier in the thread recommended that I tighten the forward lowers, so I will.

 

I wouldn't look at the rig with just a jib flying. The main adds some support to the rig and may prevent the pumping. Go oit on a day when yoi can load up the rig fairly well with both sails up.

Share this post


Link to post
Share on other sites

Ajax, if it was me..I'd unload the rig every season..but it is a cruising boat, so I don't. I just have too many higher priority items that I don't think about taking a few hours to unload the rig for the winter. :unsure:

Share this post


Link to post
Share on other sites

Most cruising boats don't crank the rig in the way the racing boys do to make unloading the rig so important. I'd still drop the load off over the winter, just not worry about it week to week.

 

Sailed an old half tonner back in the day where the owner had a problem with loosing tri-colours and the windex letting the backstays off at the dock. Always happened after a beer or two, need to be careful with those rigs...

Share this post


Link to post
Share on other sites

The reason I asked about unloading the rig, is because I'm wondering if the PO did it, and if I'm sailing with a de-tensioned rig. That would be scary! It's almost like he loosened the lowers, but left the caps at the proper tension.

 

Christ, I can't wait to get done with work, and go fix this. It's driving me nuts.

 

Re: Sailing on jib alone. I agree that this is the only time that the rig has pumped under sail, so not having the main up might have had something to do with it, but it did allow me to observe the problem.

Share this post


Link to post
Share on other sites

I think the theory is metal (shrouds) contracts when it gets cold, so you loosen the rigging for winter to avoid everything being too tight. Maryland though? Was the PO from New England?

Share this post


Link to post
Share on other sites

I think the theory is metal (shrouds) contracts when it gets cold, so you loosen the rigging for winter to avoid everything being too tight. Maryland though? Was the PO from New England?

 

But metal masts don't contract?

Share this post


Link to post
Share on other sites

I think the theory is metal (shrouds) contracts when it gets cold, so you loosen the rigging for winter to avoid everything being too tight. Maryland though? Was the PO from New England?

 

But metal masts don't contract?

 

Of course they do.

But you know how traditions get carried along over time?

With wooden masts and hemp rope for standing rigging it was probably really important to loosen rigging when the ship

was not being used. Just a change in moisture content and subsequent shrinkage could wring a mast.

Extreme temperature changes could have been even worse.

 

Now we have aluminum masts and stainless steel rope for standing rigging.

But tradition is tradition...

 

The question is does the cold tighten the rigging.

 

Metals expand and contract at a characteristic rate - referred to as the coefficient of expansion.

The change in dimension depends of the difference between the start and end temperature and the length of the material in question.

(Also, to be exact, the coefficients can change with temperature too)

dl = α L
o
dt
(1)

where

dl
= expansion (m, inches)

L
o
= length of material (m, inches)

dt
= temperature difference (
o
C,
o
F)

α
=
(m/m
o
K, in/in
o
F)

 

For aluminum the linear expansion coefficient, α =12.3 inches

For non-ferritic stainless steels (like 304 to 316) the expansion coefficient ranges from 8 to 9.6.

So right off the bat the difference in expansion coefficients suggests that there could be a problem as temperature changes.

 

But note that we also include the length of the item - Lo.

As someone up thread already pointed out, stainless rope consists of spiral wound wires, and the length is much greater than

the pin to pin length of the rope.

 

We will leave running all the calculations as an exercise for the student, but I would expect the longer strand length of the wire

rope (verses mast length) will pretty much cancel out and any differences in length due to changes in temperature will be pretty small.

 

Any takers?

Share this post


Link to post
Share on other sites

OK, I'll bite. We aren't talking about expansion, we're talking about contraction. Our delta T is negative. The aluminum mast will contract more than the SS shrouds, so the shrouds will loosen. Is this a keel stepped mast? If so, then it is even longer than the shrouds and will contract even more, no? And the change in length will be most pronounced with the lowers because the difference in length between the mast step and hounds vs. the lower shroud length is greater. Or I'm missing something. wink.gif

Share this post


Link to post
Share on other sites

OK, I'll bite. We aren't talking about expansion, we're talking about contraction. Our delta T is negative. The aluminum mast will contract more than the SS shrouds, so the shrouds will loosen. Is this a keel stepped mast? If so, then it is even longer than the shrouds and will contract even more, no? And the change in length will be most pronounced with the lowers because the difference in length between the mast step and hounds vs. the lower shroud length is greater. Or I'm missing something. wink.gif

 

In engineering terms, there is no such thing as cold.

Only varying degrees of heat.

 

Contraction is expansion - just in the other direction.

 

No, I think you have a pretty good handle on it.

At least that's the way it looks from here...

Share this post


Link to post
Share on other sites

OK, I'll bite. We aren't talking about expansion, we're talking about contraction. Our delta T is negative. The aluminum mast will contract more than the SS shrouds, so the shrouds will loosen. Is this a keel stepped mast? If so, then it is even longer than the shrouds and will contract even more, no? And the change in length will be most pronounced with the lowers because the difference in length between the mast step and hounds vs. the lower shroud length is greater. Or I'm missing something. wink.gif

 

In engineering terms, there is no such thing as cold.

Only varying degrees of heat.

 

Contraction is expansion - just in the other direction.

 

No, I think you have a pretty good handle on it.

At least that's the way it looks from here...

 

I just think his forward lowers are too loose. B)

Share this post


Link to post
Share on other sites

OK, I'll bite. We aren't talking about expansion, we're talking about contraction. Our delta T is negative. The aluminum mast will contract more than the SS shrouds, so the shrouds will loosen. Is this a keel stepped mast? If so, then it is even longer than the shrouds and will contract even more, no? And the change in length will be most pronounced with the lowers because the difference in length between the mast step and hounds vs. the lower shroud length is greater. Or I'm missing something. wink.gif

 

In engineering terms, there is no such thing as cold.

Only varying degrees of heat.

 

Contraction is expansion - just in the other direction.

 

No, I think you have a pretty good handle on it.

At least that's the way it looks from here...

 

I just think his forward lowers are too loose. B)

 

 

You may be right.

 

Obviously the resonant frequency is way too low.

That does imply a lack of stiffness - or rigidity, if you prefer.

 

I doubt that the uppers are the culprit.

That would for sure show up when sailing.

 

 

I can't wait to see what Hike finds out...

Share this post


Link to post
Share on other sites

Hike doesn't have a planned visit, he's just going to do a drive-by on me, whenever he finally has a reason to be up in Annapolis. Right now, I have the turnbuckles soaking in Kroil. They had years-old rigging tape on them that was disintigrating, depositing solid, crumbly crap on the threads, so they need a bit of love with a stiff brush and the Kroil before I adjust them.

Share this post


Link to post
Share on other sites

Hike doesn't have a planned visit, he's just going to do a drive-by on me, whenever he finally has a reason to be up in Annapolis. Right now, I have the turnbuckles soaking in Kroil. They had years-old rigging tape on them that was disintigrating, depositing solid, crumbly crap on the threads, so they need a bit of love with a stiff brush and the Kroil before I adjust them.

 

I feel your pain, Ajax. Really.

 

Today I pulled my chain-plates out (Chain-Struts, actually, in my boat).

They have been leaking - right on my belly button!

(now I can see why - there was NO sealer in there!)

 

And I had to (very carefully!) cut one bolt head to get the port deck fitting loose.

 

I'll put them back in with MainSail's Butyl Rubber Tape for a permanent seal,

and 10% more love than the boat yard would use.

 

(paraphrased from"Mom's Robot Oil" commercials)

 

 

But - do this - just for grins and giggles?

How about spiral a halyard around the lower mast section?

 

Below the spreaders, obviously, but take a dozen turns around the lower part.

Then see what happens when the wind blows?

 

May not make any difference at all, but then again...

Share this post


Link to post
Share on other sites

Another update:

 

The weather was mid 60F's, so I sailed again yesterday, in a steady 20kts of breeze. I used a #2, and a full main (because my old rag of a mainsail has no reefing method). Again, I was able to verify that the rig stays straight on each tack so I'm feeling good about the cap shrouds. The aft lowers get pretty sloppy, and the forward lowers get kind of soft. I also observed that the forestay got a tad soft. With the main up this time, there was no pumping while sailing off the wind.

 

If I can just stop giving into the temptation to go sailing, and adjust the damn forward lowers, I think I'll have this straightend out. Hopefully this afternoon.

Share this post


Link to post
Share on other sites

Ajax, do you have a backstay adjustment? I cannot remember from the 'thru-hull episode' since we were focusing on other things at the time (which wasn't really an episode, but a rather elegant 'meeting of the minds' in which we all had the proper tools to complete the job and look like rockstars..) B)

 

By the way, remember that leech tension on the main always helps to stabilize the rig, & it also gives you some headstay tension. The two wings work in unison, and if you eliminate one, you must compensate with other rig controls.

Share this post


Link to post
Share on other sites

Ajax, do you have a backstay adjustment? I cannot remember from the 'thru-hull episode' since we were focusing on other things at the time (which wasn't really an episode, but a rather elegant 'meeting of the minds' in which we all had the proper tools to complete the job and look like rockstars..) B)

 

By the way, remember that leech tension on the main always helps to stabilize the rig, & it also gives you some headstay tension. The two wings work in unison, and if you eliminate one, you must compensate with other rig controls.

 

Sorry for the late reply- No, I don't have a backstay adjustment. As Stickboy says, the mast on the P30 is a telephone pole, without a lot of flex for adjustment. You don't get much pre-bend.

 

So here's the update- I took two full turns on the forward lowers and they definitely feel a bit tighter than before. The aft lowers are still so soft, that I did not ease them to compensate for what I'm doing with the forward lowers. None of the shrouds are bar-tight, but I don't have the experience to tell if I'm overtightening things. Tightening the forward lowers did not induce any pre-bend in the mast, although I observed that if I tugged slightly on the foward lowers simultaneously, that I could induce pre-bend.

 

Should I:

 

1. Continue to tighten up the forward lowers until I have just a bit of pre-bend?

2. Snug up the backstay a bit, to work with the forward lowers to induce a bit of pre-bend?

3. Leave it the fuck alone?

 

Also, assuming I buy a Loos gauge, where can I find tension values for my rig, so I can set it correctly?? :unsure:

Share this post


Link to post
Share on other sites

Ajax, do you have a backstay adjustment? I cannot remember from the 'thru-hull episode' since we were focusing on other things at the time (which wasn't really an episode, but a rather elegant 'meeting of the minds' in which we all had the proper tools to complete the job and look like rockstars..) B)

 

By the way, remember that leech tension on the main always helps to stabilize the rig, & it also gives you some headstay tension. The two wings work in unison, and if you eliminate one, you must compensate with other rig controls.

 

Sorry for the late reply- No, I don't have a backstay adjustment. As Stickboy says, the mast on the P30 is a telephone pole, without a lot of flex for adjustment. You don't get much pre-bend.

 

So here's the update- I took two full turns on the forward lowers and they definitely feel a bit tighter than before. The aft lowers are still so soft, that I did not ease them to compensate for what I'm doing with the forward lowers. None of the shrouds are bar-tight, but I don't have the experience to tell if I'm overtightening things. Tightening the forward lowers did not induce any pre-bend in the mast, although I observed that if I tugged slightly on the foward lowers simultaneously, that I could induce pre-bend.

 

Should I:

 

1. Continue to tighten up the forward lowers until I have just a bit of pre-bend?

2. Snug up the backstay a bit, to work with the forward lowers to induce a bit of pre-bend?

3. Leave it the fuck alone?

 

Also, assuming I buy a Loos gauge, where can I find tension values for my rig, so I can set it correctly?? :unsure:

 

There are instructions with the gauge, you are tensioning to % of working strength of the wire. The main value of the gauge is that once you have the rig set you can quickly duplicate it after removing the stick or whatever.

Share this post


Link to post
Share on other sites

Ajax, do you have a backstay adjustment? I cannot remember from the 'thru-hull episode' since we were focusing on other things at the time (which wasn't really an episode, but a rather elegant 'meeting of the minds' in which we all had the proper tools to complete the job and look like rockstars..) B)

 

By the way, remember that leech tension on the main always helps to stabilize the rig, & it also gives you some headstay tension. The two wings work in unison, and if you eliminate one, you must compensate with other rig controls.

 

Sorry for the late reply- No, I don't have a backstay adjustment. As Stickboy says, the mast on the P30 is a telephone pole, without a lot of flex for adjustment. You don't get much pre-bend.

 

So here's the update- I took two full turns on the forward lowers and they definitely feel a bit tighter than before. The aft lowers are still so soft, that I did not ease them to compensate for what I'm doing with the forward lowers. None of the shrouds are bar-tight, but I don't have the experience to tell if I'm overtightening things. Tightening the forward lowers did not induce any pre-bend in the mast, although I observed that if I tugged slightly on the foward lowers simultaneously, that I could induce pre-bend.

 

Should I:

 

1. Continue to tighten up the forward lowers until I have just a bit of pre-bend?

2. Snug up the backstay a bit, to work with the forward lowers to induce a bit of pre-bend?

3. Leave it the fuck alone?

 

Also, assuming I buy a Loos gauge, where can I find tension values for my rig, so I can set it correctly?? :unsure:

 

 

Ajax,

 

For a telephone pole, a loos gauge is a waste of money, OMHO. Bendy rigs are very responsive to adjustment as conditions change and a loos gauge is a great way to get repeatable settings for expscted conditions. Stiff, masthead rigs not so much. Unless an experienced P-30 sailer tells you otherwise, start with a straight mast that stays straight athwartships under load. Most masthead rigs are designed for a touch of rake but it depends on how your helm feels. More rake moves the COE aft and adds weather helm (or takes away lee helm. Ask your sailmaker how much prebend he's building the main to fit. Luff round adds draft and mast bend flattens the main as the wind comes up. For "most" MH rigs, a bit of rake (3-5" on a 30 footer) and some slight prebend with firm headstay/backstay tension and a mast that stays in column athwartships is a decent setup for going to windward.

 

Basically, I'd set it up straight and sail the boat in 10-12 knots of wind and adjust rake and prebend to fine tune the helm and fit of the main. You might want to spend the loos gauge money on a multipart backstay adjuster.

Share this post


Link to post
Share on other sites

Ok, this is helpful. Just gotta remember to take the same amount of turns on each turnbuckle to keep tension even. The boat has a very balanced helm now, and the mast stays in column. I just wanted to get rid of the pumping, and felt that the leeward lowers were too sloppy in 15-20kt breezes (on both tacks).

 

The original (and the new) sail barely have any luff curve in them because as you say, the rig isn't very bendy. I was just looking for the barest amount of pre-bend.

Share this post


Link to post
Share on other sites

Yep, what IB said.

 

You don't need any prebend and you'll be pulling on the hull pretty hard trying to get it. Just get the forwards so that the leewards are still snug but not tight and the afts are a little soft but not flopping when at 15-20 degrees or so. Backstay adjuster is kinda nice.

Share this post


Link to post
Share on other sites

Don't waste money on a gauge. I might be up that way soon...I'll let you know when I have more details.

 

FYI- My old man sailed my 4KSB with a sloppy rig for years (all shrouds slack on the leeward side under sail and it never fell down)...pulling a shroud thru the deck is what dropped the rig in about 1987 due to a flaw in the original design. One of the first things I did to the boat was install the 3rd revision (as far as I can tell) to the shroud base offered thru Catalina Direct..Probably one of the best $175 I've spent on the boat. At any rate..a loose rig doesn't mean it will fall over...a failed shroud, however, usually does.

Share this post


Link to post
Share on other sites

Hm, ok. Based on what you guys are saying, I won't make any further adjustments until I make a test sail. I may have already corrected the issue.

Share this post


Link to post
Share on other sites

Ajax, Here is the Standing Rigging Tuning section of the C&C 37+ Owners Manual. It's pretty much standard stuff but I want to bring your attention to the following quote:

"...when the upper shrouds are at optimum tension, when at about 15 to 20 degrees of heel, the leeward rigging should look slack. This is quite appropriate and should never be tightened."

I'll include the whole section below because you may find it useful:

4.3 Tuning at the Dock

All turnbuckles are equipped with toggles at their base which eliminates bending load on the swage and turnbuckle threads. Toggles are fitted to both ends of the forestay. As the boat tacks and the headsail loading varies from side to side, the forestay terminals are subject to extreme fatigue loading"

Start tuning the spar by ensuring that the mast is in the center of the boat, pertendicular to the designed transverse waterline. Your boat may not sit level at the dock due to distribution of gear, stores and tankage levels, so check the waterline position both sides. Then slacken the lower shrouds completely by undoing their turnbuckles. Take the main halyard and lead the shackle end to a point on the rail or chainplate. Adjust the halyard so that the shackle just touches the reference point on the rail or chainplate with a given downward tension, and then cleat the halyard. Then take the halyard to the same reference point on the other side of the deck. With the same amount of downward tension, you will be able to just touch the shackle to the reference point if the mast is plumb transversely. lf not, let off one upper shroud turnbuckle and lake up on the other in order to bring the masthead closer to centerline until the halyard shackle touches both reference points under the same downward tension. The particular part of the rail or deck you choose as your reference point is not important as long as it is the same point on each side. Once the mast is centered transversely, tighten both upper shroud turnbuckles uniformly, one full turn one side, then one full turn on the other. Repeat until the turnbuckles become difficult to turn. Pin the turnbuckles. Tighten the lower shroud turnbuckles so that almost all of the slack is removed; the center point of each lower shroud should have about 1 inch of play in either direction. Sight up the aft side of the mast to make sure that it is straight. The lower shrouds may require adjustment to straighten the mast.

Now check the rake. Rake is the fore and aft angle of the spar. The C&C 37+ spar is designed to carry up to (approx.l 12 inches of rake. Rake effects the position of the center of effort of your sail plan and, consequently, the balance of the helm. The effects are more pronounced in heavier winds. The extent of rake on your boat should be determined by your particular sailing characteristics, the typical local wind conditions and your sailmaker's suggestions.

Forward rake should be avoided. The main halyard may be used to measure rake. In calm wind and sea, with the boat floating level on her lines, hang a plumb weight or equivalent, such as a hammer or wrench, from the main halyard. Adjust the halyard so that the weight is suspended just above the gooseneck. The fore and aft distance between the mast and the halyard at the gooseneck level is the amount of rake. Ease off the forestay turnbuckle and tighten the backstay turnbuckle (or vice versa) until the desired rake is achieved. Pin both fore and backstay turnbuckles.

Unless the rake has to be readjusted in the future to correcl helm balance, these turnbuckles will need no more adjusting. Additional tensioning may be applied by the backstay adjuster.

Check that the outboard ends of the spreaders are padded and taped to avoid chafing the genoa.

Ensure that all turnbuckles are pinned. The mast should be fixed at the step to prevent fore and aft movement and to hold the mast in the step.

You are now ready to complele the tuning procedure while sailing.
4.4 Tuning While Sailing

Select a day with a steady I to 12 knot breeze and reasonably flat sea. Put the boat on starboard tack, close hauled. Sight up the luff groove of the mast. If the mast seems to fall off to leeward at the spreaders, luff up slightly and tighten the starboard lower shroud as necessary. Put the boat back on the wind and check the spar again, adjusting as necessary. When the mast appears straight, bring the boat about and do the same on the port side.

Check the following carefully.

First, when the upper shrouds are at optimum tension, when at about 15 to 20 degrees of heel, the leeward rigging should look slack. This is quite appropriate and should never be tightened.
Secondly, when close hauled under genoa and main, the forestay may appear quite sagged. Tensioning the backstay will reduce the amount of sag, but the sag itself can never be eliminated. As a rule of thumb, the maximum static backstay pressure should never exceed one quarter of the backstay breaking strength. (See table 2, Standing Rigging and Table 5, Backstay Preload Limits.)

lf your boat is brand new, the rigging may seat and stretch to the extent that tuning from scratch again will become necessary in a matter of weeks. However, after this initial working-in period, you will find that the rig tends to hold its tune for considerably long periods of time. After becoming used to the feel of the boat, you may wish to either increase or decrease the amount of weather helm. Any sailboat, when sailing up wind, should have a slight tendency to "round up" or head into the wind if the helm is let go. However, if you find it typically difficult to hold the boat off the wind, the boat is carrying to much weather helm. This can be alleviated by reducing rake which will move the center of effort of the sailplan further forward" Conversely, if you find the boat tends to fall off when sailing upwind and you must constantly push her to weather, then the boat carries lee helm and the rig will require more rake.

With constant tuning as the season progresses, your boat's performance will improve. The boat will feel more comfortable to sail.

You will find that tuning is a bit of an art, yet you will begin to notice subtle changes in the behaviour and response of your boat as you make subile changes in tuning. The important thing to remember is to go about the process in a slow and orderly fashion. To record the details of the tuning and retuning procedures as well as the results achieved will provide you a better understanding of the rig and will serve as a useful reference for rigging the boat on subsequent occasions.

Share this post


Link to post
Share on other sites

Wow, thanks Ken. I'll print this out and bring it down to the boat. These instructions seem safely generic enough for an older, masthead boat with telephone pole mast.

 

Ugh, I'm starting to think that nothing was wrong at all! But I still don't understand the pumping at the dock, and it doesn't seem to be a common problem with the P30. It was windy as hell today, but I didn't get to the boat to see if it's still happening now that I snugged up the lowers.

Share this post


Link to post
Share on other sites

Ajax, the pumping is prolly cuz the rig was too loose..not to fret though...just snug everything down. After it is all snug, put one extra turn on the uppers and you are good to go.

Share this post


Link to post
Share on other sites

both the 26 and the 30 would pump once in a while. like I said, it would never quite reach climax but it always felt like it was just about to. Probably only once or twice a year but when it was going on it was really something. I can't remember if it was Beau or who it was that mentioned it but wrapping a halyard arond the mast just to break up the flow would probably get you through an uncomfortable night.

Share this post


Link to post
Share on other sites

Ajax I've been folowing this for a bit and I'm getting the feeling that the whole rig is just loose. Get a local fellow anarchist to get a second opion from and / or walk the dock and feel how tight other boats are, Your not tuning and open 60 or nothing.

 

The last time your boat had a new sail on it was when Adam was still a Cowboy, I'm guessing the rig was cheaked at about the same time, things loosen over time and need adjusting.

 

If your not going to tighten it up something stupid you won't break it, Your a bright guy - think about what you are doing and do it, you'll be fine.

Share this post


Link to post
Share on other sites