Cynical sailor

Aft mainsheet

Recommended Posts

Take a look at almost all catamaran mainsheet systems.  Lots of pictures in ads, etc. I got so used to it that I converted my Windmill and now a Raider. Lots of room and a longer tiller extension resulted.   Dave Ellis

Share this post


Link to post
Share on other sites

You should just copy a skiff system. Use a bridle (maybe adjustable) across the transom, probably fix a pulley in the middle. 2:1 purchase should be sufficient. Sheet goes boom to bridle, back to boom, then along to another pulley about where the current main sheet is. To lessen the overall length of the sheet, you might want to hang the bridle pulley off the bridle using a tether so it's close to the boo m when sheeted fully on. It will reduce the overall length of the sheet by twice the length of the tether.

Very easily converted to 3:1 if you need to, but probably not. I think the main sheet on a Vag is only 3.:1 (but I haven't sailed one in quite some time…).

You'll need a film tube on the boom as a conduit to contain the sheet running underneath, otherwise you'll garrote yourself when gybing occasionally. You should be able to mock it up pretty easily to get things in the right place before making it more permanent. One issue is that when capsized, the sheet tail will be on boom rather than in the middle of the boat, making it harder to reach initially. But that may not be an issue.

 

IMG_2281.JPG.2c4728cd47fadfb85f35ac177a0ee272.JPG

Share this post


Link to post
Share on other sites

Or, what I did once on my 18ft trailer sailer was the bridle like above except that it was made up by two tails coming out of the end of the mainsheet.

Each tail went to the outside deck and was adjustable.

Adjustable so that the tail became the mainsheet as the mainsheet went through the block on the boom.  That was it - a 2:1 mainsheet where most other racers used 4:1 on a traveller on the pushpit.  It was very fast.

Also, because the effort was taken up by the windward tail the 2:1 effort was much easier - you were never pulling the boom down (that was the job of the 32:1 vang) just pulling it towards the windward deck.

So compared to the drawing you lose two of the three blocks and don't have the garrotting tool along the boom.

KO

Share this post


Link to post
Share on other sites

Vagabond vangs are totally shit, maybe 3 or 4:1, you need to crank on the mainsheet fully to get them anywhere near "on". A decent heave at 32:1 would either crush the gooseneck or bend the boom.

Leaving the mainsheet off the end of the boom also means only the helm can use it, otherwise it presents a trip/choking hazard in tacks and gybes. Maybe not an issue on a trailer sailer, but not ergonomically optimal on a 14' dinghy.

Anyhow, I'm sure the OP can work it out.

Share this post


Link to post
Share on other sites

First, thanks to all who weighed in on this. This is all new to me (first boat) so bear with me.

RobG's sketches appear to show the end of the sheet still going through block at mid-boom. I'll back up a bit and outline the impetus for this effort: My wife has a bad back and needs to sit facing forward. I'm trying to free up the middle of the cockpit by moving mainsheet to the aft end of the boat, so I can put a low seat just behind the trunk where the mainsheet block is now.

Share this post


Link to post
Share on other sites

If you're just daysailing moderate/light wind, I would try without the vang and move her forward. Or make the vang triangle smaller. If you are the only movable ballast we want to keep you mobile.

Boats sail shitty without a vang but they do sail. 

Share this post


Link to post
Share on other sites
45 minutes ago, Dex Sawash said:

If you're just daysailing moderate/light wind, I would try without the vang and move her forward. Or make the vang triangle smaller. If you are the only movable ballast we want to keep you mobile.

Boats sail shitty without a vang but they do sail. 

In addition to losing the vang, she'll be positioned right over the daggerboard, restricting my ability to lift it - we sometimes sail in shallow waters. Maybe I need a different boat that allows for forward-facing crew.

Share this post


Link to post
Share on other sites

If you just want to try out a conventional stern main on a 14ft dinghy, then all you need to do is create a bridle as shown in the sketches, and have two single blocks, one with a becket. The block with becket goes on the bridle and up to the other block on the boom, then back down to the block on the bridle, and then to hand. You should have enough blacks to fabricate that without spending significant money, and see how you get on with it. If it works for you then you might want a ratchet block for the one on the bridle. The thing about this as the helm, though, is that you need to tack facing backwards, not forwards.

That's kind like RobGs top drawing upside down. I'd be kinda inclined, though, to first try RobGs top drawing where the mainsheet goes along the boom and finishes up on a block on the boom, coming off the boom to hand, and not going back to the centreboard trunk. That way you lose the junk on the centreboard trunk, and you can have the block a bit futrher back on the boom if you like, but you don't need to learn to tack facing the other way.

The conventional setup in this country for a two hander in the old days, BTW, used to be to have a thwart (seat) right across from side tank to side tank aft of the centreboard slot. Seems to me that's what your wife needs. As good an example as any of the setup is the old Mirror dinghy. See here

http://sailboatdata.com/viewrecord.asp?class_id=3824

 

 

Share this post


Link to post
Share on other sites

i don't know the vagabond but the old Vaurien set up might work for you... I'll try to find a better picture. The sheet goes from the block on starboard of the helm to a ratchet block on the bottom of the boat.(not shown)

 

6650867290648f9ab8036d152ede3bfd--honfle

Share this post


Link to post
Share on other sites

Easy-peasey - I hope this is legible. This one is deadened on the port side, up through a block on the boom, then down through a ratchet block on the starboard side. You could add purchase if you want by having a block with a becket on the boom, run the mainsheet from the becket through a block on the port side of the transom then back up through the block on the end of the boom, the down through a ratchet block on the starboard side. There are a ratchet/cleat assemblies you an use, but without a stable base it might be difficult to cleat/uncleat.

 

Enterprise Dinghy photo on sailboatdata.com

Share this post


Link to post
Share on other sites

The main trouble I used to find with the setup on the Vaurien and that early Enterprise is that it was annoyingly imprecise.

How is your boat set up at the moment? I've seen some photos which appear to show a Vagabond 14 with a bridle just inboard from the transom. Is yours a stern to centre setup, or is it all in the middle of the boom?

Share this post


Link to post
Share on other sites

And transom sheeting pretty much forces you to turn and look backward when you tack. This can result in some  sloppy maneuvers. Less than ideal - cat sailors don't have that much problem with the mainsheet aft because the boat slows dramatically (if not to a stop...)  when you go head to wind.

Share this post


Link to post
Share on other sites

Right, oh well, that's easy.

The first thing I'd try would be to simply undo the mainsheet from the floor, and take it straight from the boom. If the way the block is fastened to the boom doesn't let it swivel enough simply lash another one to the boom. You could move it some inches further back if you do that too. If you do choose to move the block back then a bit of light line to the existing fitting will stop it moving further back than intended. Taking the mainsheet from the boom is now very fashionable!

If that still wasn't satisfactory then a straight stern main can be done simply by swapping the two blocks round!

Depending on your carpentry, a thwart that's lower in the middle but higher at the sidedecks can be fabricated by laminating up a few layers of thin plywood.

Share this post


Link to post
Share on other sites

The block on the middle of the boom and down behind the case do nothing for gearing, they are just leading the sheet forward which is the current 'style'.

If one of the blocks on the end of the boom was a ratchet block then you'll have the benefit of less rope and less stuff at the front so the good wife doesn't get tangled.

Worth a try, as they say above you'll need to work out new tacking choreography.

On the cats (like the one in my avatar) the tiller is in the middle of the dual rudder setup and you effectively throw the extension out the back when you're tacking and as noted above tacking is quite a dark art because there are no centreboards and the boat nearly stops dead.

Share this post


Link to post
Share on other sites

On boats where I use the main sheet off the traveler back there, I used a bent tiller. It dips under the traveler.     And, yes I do have a cam cleat on the stacked double block at the traveler. I face forward when tacking or jibing. Hmmm. Maybe now that they say it can't be done I'll get all tangled up!  Dave Ellis

Share this post


Link to post
Share on other sites

Hmm. Yup - you are right. I stand corrected. It just needs the old double switcheroo of the the tiller and main sheet behind the back. I had to dig into my memory vault of sailing the 70's  FJs we had at the club. They were rigged exactly like the Enterprise in the photo.

Share this post


Link to post
Share on other sites
15 hours ago, Cynical sailor said:

In addition to losing the vang, she'll be positioned right over the daggerboard, restricting my ability to lift it - we sometimes sail in shallow waters. Maybe I need a different boat that allows for forward-facing crew.

All the Vagabonds I've seen have a swing-up centreboard, not a daggerboard. Sitting on the case isn't an issue. Forgetting which line pulls the board up and which puts it down is. ;-)

If you want to sheet off the end of the boom, just remove the block in the middle of the boom in the sketch. It would be best to have the sheet starting at a becket on the bridle, then to the boom and back to a pulley on the bridle (i.e. swap the blocks in Cynical sailor's photo and remove the one in the middle of the boom). That way when the boom is fully out (e.g. going dead down wind) the tail of the sheet is in the middle of the transom, not out at the end of the boom. The tiller goes under the bridle.

Share this post


Link to post
Share on other sites

I wish it had a swing-up centerboard, but it doesn't. That changed when it became the Hobie Holder 14 MKII. I'm going to take JimC's advice and just undo the mainsheet from the floor and bring it to hand straight from block at mid-boom. Move the block aft a bit and change to a ratchet.

 

Share this post


Link to post
Share on other sites

At the risk of being the bearer of bad news, I can say for sure that you have the wrong boat for your wife.

The main sheet rigging is only a minor detail compared to what is coming next. How do I know this? I just spent the last year sailing one with my wife. 

The real issue is that the cockpit is too small for mature adults and you will find that the combination of the tall daggerboard trunk in the same area where the jib sheet ends makes for a lot of tripping and confusion if she isn't an experienced sailor. Add to that the front cubby is blocked off for front flotation means even half a kayak paddle will  not fit and becomes a tripping hazard.  

 One other thing that is not really bad design wise, but may be an issue for you, is that the original daggerboard is a several inches too long at roughly 58.5 inches. That makes the boat a little tender, even with the 6 foot wide beam. Don't get me wrong, it is nearly impossible to capsize while sailing, but it heals over enough before it settles into it's happy place that it can make a mature woman freak out. This is especially bad if she is sitting on the jib sheet that she should be releasing. 

 The good news is it is a very well made boat that stays 100% dry between the hulls and if it doesn't it is always just a bead of silicone  behind the cubby wall (near the weep holes) or the O-ring at the drain plug. I also can tell you for sure that 50 inches is the best daggerboard length from handle to the tip for pointing upwind. It's also one of the best balanced helm when planed off that I've ever sailed and righting it when capsized is easier than a Sunfish. ( I have only  been over once while sailing, and that one was a pole vault off the daggerboard and once I pulled it over to retrieve the up-haul line.)

  I'm going to advise against sailing with a ratchet block only, as the sheet loads a little high to hold for long runs. It is also easier to untangle the wife from the jib sheet when cleated (assuming you have a tiller lock or bunji).

 So which trailerable boat am I buying to sail with my wife? It's probably an O'day Daysailer 2 at 17' or a Rhodes/Mariner CB at 19'. I also wouldn't rule out a Precision 18. if it was cheap. 

 I have borrowed a DS2 and that was a very relaxing sail without all the stress. It also had the jib cleats on the kick-up center-board case the made life much easier for her. What an amazing difference for her with a boat the only weighs 100 lbs more. Also both the DS2 and the Mariner will sail with the main only. The Holder is very hard to tack without the jib.

Share this post


Link to post
Share on other sites

Thanks for your detailed reply  unfortunately another boat is not in the budget, nor are many options available to buy locally. Does a shorter dagger board increase possibility of tipping? I did manage to capsize once, but it was a gusty day (of course operator error might have been in the equation. I’ve not found that holding the main sheet for any length of time to be a problem, and I’m reluctant to cleat it. 

We’ll see how it goes for now. 

 

 

 

Share this post


Link to post
Share on other sites
36 minutes ago, Cynical sailor said:

 Does a shorter dagger board increase possibility of tipping?

On the contrary. Daggerboards are partly lifted up in rough conditions to prevent capsizes.

Edited by Suppenkelle
clarity

Share this post


Link to post
Share on other sites
On 12/6/2017 at 11:57 AM, Dex Sawash said:

If you're just daysailing moderate/light wind, I would try without the vang and move her forward. Or make the vang triangle smaller. If you are the only movable ballast we want to keep you mobile.

Boats sail shitty without a vang but they do sail. 

i would not sail the vast majority of boats without vangs. A typical sailboat design like this one does fall under that exception. Most beach cats do. It just makes most boats too obnoxious to handle downwind/maneuver downwind without a vang.

Share this post


Link to post
Share on other sites

I sailed the cat in my avatar with a vang.  Was a great advantage dead downwind, however, the big downside was upwind because the vang (dependant on setting - ie forgetting to let it right off at the end of the leg) wouldn't let the mast unbend which it needed to do in order to gybe over onto the next tack so got stuck with the rotation on the old tack!  Also on the odd occasions when I capsized it was a huge problem because it wouldn't let the boom off enough to clear the water out of the sail.

It's now gonsky.

Share this post


Link to post
Share on other sites
19 hours ago, Suppenkelle said:

On the contrary. Daggerboards are partly lifted up in rough conditions to prevent capsizes.

 

19 hours ago, Cynical sailor said:

 Does a shorter dagger board increase possibility of tipping?

It doesn't make a huge amount of difference either way. Some of the faster boats sail with the board down all the time as does, of course, every keelboat. I wouldn't worry about the subject IIWY. Daggerboards are lifted in strong winds more because the boat doesn't need so much foil in the water travelling fast, so lifting it makes it a fraction faster. If a daggerboard is too small the main effect are problems tacking and at low speed.

Share this post


Link to post
Share on other sites
On 12/10/2017 at 11:26 AM, Suppenkelle said:

On the contrary. Daggerboards are partly lifted up in rough conditions to prevent capsizes.

So, hydrodynamics 101: Why does having less board in the water help prevent capsizing?

Share this post


Link to post
Share on other sites
16 minutes ago, Cynical sailor said:

So, hydrodynamics 101: Why does having less board in the water help prevent capsizing?

Lift. It's all about equilibrium of forces... I remember a race, downwind, on a Mistral OD windsurf board with a fresh breeze. I stepped (pushed) the daggerdoard down just before the leeward mark, but clearly to soon: the board literally jumped up  when the blade went down... I was planing and the lift generated by the daggerboard totally launched my up in the air.

Share this post


Link to post
Share on other sites
On ‎12‎/‎12‎/‎2017 at 4:56 PM, Cynical sailor said:

So, hydrodynamics 101: Why does having less board in the water help prevent capsizing?

Not so much hydrodynamics as physics. If the board is up, the boat will slip sideways more easily rather than heeling. So the force of the wind is effectively absorbed by sideways drift as opposed to heeling further.

Share this post


Link to post
Share on other sites
1 hour ago, bill4 said:

Not so much hydrodynamics as physics. If the board is up, the boat will slip sideways more easily rather than heeling. So the force of the wind is effectively absorbed by sideways drift as opposed to heeling further.

Its certainly Physics, but that's really not a good description of what's going on. A boat doesn't really slip sideways at all. It certainly does't drift sideways in the way you describe. Well, not unless the foils are stalled out and doing nothing much.

What has traditionally been called leeway, and thought of as a boat slipping sideways is really nothing of the sort. A conventional boat has a symmettrical lifting surface in the water, and because its symmetrical it must run at an angle of attack to the oncoming water to generate lift. This angle of attack means that the boat must sail with the waterflow at a slight angle to the centreline. No angle, no lift, no can sail.

The amount of lift must balance the forces produced by the rig. so if you have a generous sized efficient foil the angle of attack is very small. If you reduce the foil size drastically a point is reached where the remaining foil has to start working very hard, and the angle of attack must be increased noticeably to generate the same lift. To maintain the same course through the water the bow must point closer to the wind than before. Superficially it seems as if the boat is now going sideways, but its not. If you could rotate the daggerboard relative to the hull you'd find you were on the same course as before.

What does make a certain amount if difference is heeling moment. If you have say 3ft of daggerboard under the hull the lift averages out say 18inches below the hull. If you have 1ft of daggerboard then the the lift averages out 6 inches below the hull. So if the centre of lift from the sails is ten feet above the deck then the lever between sail lift and foil lift goes down to 10ft 6 from 11ft 6, which does make a bit of difference.

Share this post


Link to post
Share on other sites

Thanks for the physics lesson! As I understand it, if the drag and lift are balanced, the boat moves forward in the most efficient (fastest) manner. What causes heeling? Does reducing the amount of daggerboard in the water decrease lift and reduce heeling? Does reducing drag (easing the mainsheet) accomplish the same thing?

Share this post


Link to post
Share on other sites

My strong opinion on the daggerboard length of the Holder 14 comes from two different things. One is the common sailing technique of lifting the board when over powered. I've had to use this a few times when over powered and it works pretty much like the old times said it would, heeling a bit less and having a little give in the big hits. I could say it's a reduction in leverage from the boats roll center, but the truth is I have no idea other than it worked when I needed it.

The second part comes from racing every Sunday this Summer in our club races. We are scored using Portsmouth numbers, but a dozen of our racers are a  one design fleet of O'day Daysailors who are so competitive that they have strong opinions on everything. They are also amazingly accurate on some things. So what does that have to do with a Holder? It tells me a lot in race conditions. I know which Daysailors I can keep up with and at what speed I suffer in comparison. So I tested different board positions, different sail trim, body position on the boat , heeling VS sailing flat. So the short version is, on  an triangle course with a directly upwind leg, with wind speeds between 12~18 knots,  50~51 inches is the sweet spot for pointing ability. My only other comment is that the Holder was sold by Hobie both with and without a vang. I had no vang on mine and I only missed it over 20 knots and then I REALLY missed it.

Share this post


Link to post
Share on other sites
On 12/14/2017 at 6:17 PM, Cynical sailor said:

Thanks for the physics lesson! As I understand it, if the drag and lift are balanced, the boat moves forward in the most efficient (fastest) manner. What causes heeling? Does reducing the amount of daggerboard in the water decrease lift and reduce heeling? Does reducing drag (easing the mainsheet) accomplish the same thing?

Basically the lift in the sails is also pushing the rig away from the wind, and the lift from the foils is pushing the foils towards the wind. The lever between the two causes the heeling force.

The forces involved - lift from sails and foil, and righting moment from crew/hull opposing it must balance. 

Lift the board a bit and you have

i) a shorter lever, so a bit less heeling force

and

ii)less board touching the water  =less wetted area = less frictional drag. Its much more complicated than that due to other forms of drag, but that's a useful first pass.*

easing the mainsheet doesn't really reduce drag**, but it does reduce the heeling force from the sail. On boats that reef sails reefing both shortens the leverage and reduces the force in the sail, so doubly effective.

 

* the physics of sailing gets extremely complicated extremely quickly. Fortunately there are plenty of great sailors who only have a very rudimentary understanding of it, so don't get into it unless you think a combination of large quantities of maths , trigonometry, aerodynamics, hydrodynamics and basic physics sounds like an entertaining subject of study.

** typically drag increases, but that's a complication too far for now.

Share this post


Link to post
Share on other sites

Sounds like you need a Windrider 17. Has forward facing seats with back rests, no moving around needed, its a trimaran so it is extremely stable. Controls are all led back to the guy driving. It's very dry, there is even a windshield available, and best of all it is pretty fast. I love mine and my non sailing wife likes to go with me. Very drama free sailing. I run it up on the beach to get in and out of it, no centerboards to worry about. Got a small outboard to get in and out of the marina or to come back in if the wind dies. We are in our 60's and I cannot think of a better small day sailor for us. They have been around for awhile so you can find them used pretty easily.

My favorite thing about it is when a gust hits, it doesn't heel over it just powers up and accelerates. Never get tired of that. Doesn't point as well as a monohull but its loads faster and ghosts along pretty well with a whisper of air.  

I don't have any connection to Windrider I'm just a satisfied customer. 

Share this post


Link to post
Share on other sites
1 hour ago, JimC said:

Basically the lift in the sails is also pushing the rig away from the wind, and the lift from the foils is pushing the foils towards the wind. The lever between the two causes the heeling force.

The forces involved - lift from sails and foil, and righting moment from crew/hull opposing it must balance. 

Lift the board a bit and you have

i) a shorter lever, so a bit less heeling force

On boats that reef sails reefing both shortens the leverage and reduces the force in the sail, so doubly effective.

* the physics of sailing gets extremely complicated extremely quickly. Fortunately there are plenty of great sailors who only have a very rudimentary understanding of it, so don't get into it unless you think a combination of large quantities of maths , trigonometry, aerodynamics, hydrodynamics and basic physics sounds like an entertaining subject of study.

That's an excellent explanation of how heeling force increases/decreases. Thank you! I can see how reefing could be useful, too. For now, we're taking it slow and avoiding really windy days. I already ended up in the water once...

78FB1EFE-2478-4BA6-8E82-47CDB0A13C53.jpg

Share this post


Link to post
Share on other sites

There is another factor and that is balance, particularly with a cat rig. As you let the sheet out, the center of effort moves aft when the front of the sail luffs. Lifting the board moves the center of lateral plane aft, particularly with a centerboard VS a dagger board. But even with a daggerboard, the boat has reduced weather helm. A good heavy air trick in multihulls is to raise the board in the leeward hull and leave the windward board down.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now