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 I'm mulling on how to fix this. Options:

1. Some kind of composite/glass/bondo bodge-up, then use a strop around the boom for my main sheet.

2. Aluminum backing plate. Weld around the edges and then either fill with weld - use bales again for mainsheet, or fill with bondo and use a strop.

I'd like the outcome to be reasonably cosmetically good. Being strong enough to use bales again for mainsheeting is a bit of a bonus - most folks seem to be moving to strops anyway.  Ideas/advice?

 

 

boom slot.jpg

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43 minutes ago, ExOmo said:

So that was where the mainsheet bail was thru bolted?

Yes. 30 years of salt and pressure and the stainless bolt holding the bail has drawn itself through the alloy. Hall don't make this section any more so I prefer to repair this one rather than get a new boom - it's otherwise in pretty good shape, just needs repainting. Trying to decide whether to weld it or use filler. Filler has a longevity problem and issue with getting material to adhere on the inside. But it's easy to use. My welding is "patchy" at best because I never get to practice and I was never an expert anyway, so there's a fair chance of a fuckup if I do that, but I think it will have a better outcome overall. I'm looking for other ideas in case I missed an option that has worked for someone before. For example, I could weld in thick wall tube that goes all the way across the boom, or just pull a small plate over the back of the hole and weld around the edges, then fill the divot with weld. Or something else...

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Have a pro weld in the tube then finish it pretty with some epoxy filler.

Having doubler plates welded on both sides of the boom to thicken the area would also help.

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BEST: Strip whole boom raw, weld in tapered reinforcements, then heat treat.

OK: bog, smooth, and strop.

DUNNO: mill oversized oblong holes to eliminate cracks/tears, then insert matching oblong section cross block with pivoting pin through a slightly wider mainsheet bale.

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Folks - when you weld 6000 series aluminum (typical boom/mast extrusions) the yield strength drops significantly. Yield drops from something like 34 ksi to 20 ksi in the welded area. So you think you're making the boom stronger but you're locally weakening it. This is why most good mast fittings are bolted or riveted on.

So... welding a cosmetic patch isn't too wise. So my suggestions is pop rivet an aluminum painted cover plate (1 rivet at each corner looks tidy) and then use a strop for the mainsheet itself.

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Old J-22 booms often have wallowed out holes as shown at the vang and mainsheet bales. 
 

i haven’t previously  seen one as bad as the OP’s example. 

Our go to welder guy has been piling aluminum around our wallowed out holes for  us.

His creation looks like somebody mashed a Hershey’s kiss into the hole. 
 

as the original J-22 bales had a 1/4 inch through bolt I figure more bearing surface is great.

we replace the through bolt with a 3/8” bolt. 
we make certain the shank on the bolt is long enough such that neither the boom nor the bale rides on threads. 
 

if your boom were my problem I would look through my extrusion pile  for a clean chunk of extrusion and, if I found something decent, move all my hardware to a fresh extrusion 
 

As it is a mainsheet attachment, I would  consider moving the bale about 6” aft and reinstalling it with a thicker bolt. Buying a new bake with larger holes so as to create a better beating surface wouid be a good option. 
 

if those options were not available I might slide a two foot long sleeve inside and simply drill a new hole for my bale’s bolt. At least that solution would  be spreading the load well away from the old holes and might preserve my old tited boom. 

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Mechanical fasteners, particularly rivets, might work here. You could probably get the old bail to work bolted through riveted on SS plates. Nicely polished they might look spiffy, too. Riveting on an AL sleeve or patch depending also seems reasonable.

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I had this same issue, just not quite as bad. I just just cleaned up the area, left the hole, painted it and used a strop. I will not be going back. If you want to make it really pretty, fairing it out with filler (thickened on the inside as you have access) and painting it seems to be the way to go.

 

And strops are the way to go. I used some 3/16" SK78 with dyneema cover and it almost still looks new after 5 years except for a bit of staining. Weighs less as well... 

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Yeah - I'm starting to think that the filler idea is better than welding. Lower chance of a fuckup. Here's the plan:

1. Take some FR4 PCB material (or thin G10), cut a little oversize and put a screw in the middle

2. Scrub up the damaged boom around the hole so it's nice and clean with fresh bright alloy showing inside (as much as feasible) and outside

3. Epoxy the FR4 to the inside of the boom - pull it tight against the inner wall with string pulling on the screw head

4. Remove screw, fill boom divot and screw hole with epoxy filler, fair, paint

5. Use a dynema climbing sling (20KN for $10) as a strop, held in place with a stainless slug and a screw into the track on top.

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1 hour ago, Wet Spreaders said:

Yeah - I'm starting to think that the filler idea is better than welding. Lower chance of a fuckup. Here's the plan:

1. Take some FR4 PCB material (or thin G10), cut a little oversize and put a screw in the middle

2. Scrub up the damaged boom around the hole so it's nice and clean with fresh bright alloy showing inside (as much as feasible) and outside

3. Epoxy the FR4 to the inside of the boom - pull it tight against the inner wall with string pulling on the screw head

4. Remove screw, fill boom divot and screw hole with epoxy filler, fair, paint

5. Use a dynema climbing sling (20KN for $10) as a strop, held in place with a stainless slug and a screw into the track on top.

Climbing gear usually not as UV resistant as marine rated…but if it lives under a boom/mainsail cover, then maybe no big deal?

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On 1/2/2022 at 2:07 PM, Zonker said:

Folks - when you weld 6000 series aluminum (typical boom/mast extrusions) the yield strength drops significantly. Yield drops from something like 34 ksi to 20 ksi in the welded area. So you think you're making the boom stronger but you're locally weakening it. This is why most good mast fittings are bolted or riveted on.

So... welding a cosmetic patch isn't too wise. So my suggestions is pop rivet an aluminum painted cover plate (1 rivet at each corner looks tidy) and then use a strop for the mainsheet itself.

But is it 6000 series? I wouldn't weld it if it were, but some 5000 series aren't nearly that bad after welding. Maybe Hall can tell you, or you can have it tested. Also depends a bit on where the patch is. In some areas on a boom neither strength nor stiffness matter, some areas one or the other. The stiffness will not change much in the HAZ. For example if this is near the end of the boom, a 1/2 reduction in strength may not matter much - the section is way bigger than it needs to be there. 

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Almost certainly 6061-T6 or some closely related 6000 series for 95% of mast/boom extrusions.

You can't (easily) extrude 5000 series especially big sections like mast and booms. More common in small sections like flat bars and angles. That's why you see 5000 in rolled plates and some stiffeners in aluminum boats but all the pipes are 6000 series.

Good point - if the bail is in the middle of the boom depth there is not much bending going on; but there is still shear forces. 

I still think a webbing strop is wisest. Spreads the load nicely, easy to inspect etc etc.

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The boom is probably not under a lot of load at this point - the mainsheet has a 4:1 on the coarse tune and 6:1 on the fine. In a blow, I need both arms to pull the main in the last little bit, and I can probably row 160 lbs in a one off. So let's say 200 lbs max on the sheet, which means 800 lbs at the bail. Most of the tension will be along the underside, and the holes are 2ft from the end of the boom - so 1600 lb ft. That does not seem too bad for (say - bottom half of boom) 8 linear inches of (say) 1/16th aluminum with 34KSI strength. - 0.5 sq in = 3200 PSI. So it's a 10x safety factor.

 

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Right - it isn't just the location of the hole in the section, but how far from the end that is important. If the hole is very near the end, then all the aluminum has to do is stand up to the bearing of the bolts going through. I'd weld in a tube for that to increase bearing beyond the thickness of the walls (which should have been done from the beginning, then you wouldn't have this problem). If this was a vang attachment, then the strength might be critical as the bending stress is high. 

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It's bearing strength you have to worry about, not a linear tensile tear.

That's the failure mechanism of the original setup which wasn't adequate.

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57 minutes ago, Zonker said:

It's bearing strength you have to worry about, not a linear tensile tear.

That's the failure mechanism of the original setup which wasn't adequate.

Not going back to bails. I was thinking about the strength needed in the boom and the strength of the strop. It looks like a 22,000 N strop would be fine considering 800lb is about 3500N - so plenty of over-design.

I wonder whether the strop can generate the same force as bails into the mast - how are boats usually set up for that? Do we rely on vang pressure only to create bend down low?

 

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Hmm, I think I'm missing what you're asking. The strop just replaces a bail.

The strop takes the mainsheet load into the boom. It's pretty much a vertical force with a bit sideways when the boom is way outboard. Not much horizontal force going into the mast. 

 

image.png.37ba2e68b3495387d6949427066a7deb.png

 

 

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6 hours ago, Wet Spreaders said:

...the holes are 2ft from the end of the boom...

Good access, so pop the end cap and and reach inside with a flapper wheel on a drill extension. You should be able to scuff it up nicely for good tooth, then epoxy in some internal reinforcement. If you do one side first with the hole facing down, gravity should help your layup okay flat. Cure, rotate 180 degrees, then repeat. With the inside reinforced, make a cosmetic fill of the remaining divots so your strop doesn't hang-up.

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Scuffed up the outside, scuffed up the inside (Dremel taped to a stick, with flappy wheel). Epoxy 1/16th G10 sheet to the inside. Fill with epoxy loaded with filler on the outside. Waiting for it to properly harden - will sand and see what I have tomorrow.

 

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5 hours ago, DDW said:

Keeping the strops in place is one thing you have to solve. Padeyes, lashings, something - they won't stay put on their own. 

Yeah - pressing the "easy-button" would be to screw a small padeye to the top of the boom. Neater and nicer would be to screw a padeye into the track so that it's mostly hidden. I have seen another solution where a piece of dyneema is threaded through the boom - trapped on the top by a small piece of stainless rod. It looks really neat, but I worry about hidden chafe and also fouling the outhaul.

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Not too sure about this tack, but I wonder if you could use a couple of the harken gizmos or some other type fitting. The enlarged hole might cover the current oblonged ones, one on each side, maybe a spacer might be needed for the thickness but the thing would be held to the boom by thread compression. Could then run dyneema with spliced eyes through it to the block. 

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Boom looking very spiffy in its yellow ochre zinc primer. I'm planning to spray some regular grey primer over the top to fill scratches and imperfections. The paint says "thin with Xylene", which I can't get in the People's Republic of California. What to use instead?

 

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1 hour ago, Wet Spreaders said:

Boom looking very spiffy in its yellow ochre zinc primer. I'm planning to spray some regular grey primer over the top to fill scratches and imperfections. The paint says "thin with Xylene", which I can't get in the People's Republic of California. What to use instead?

 

WTF kind of paint are you using? xylene & toulene are the fastest evaporating solvents. They use it in spray paint & carb cleaner. 
 

Acetone is very fast as well. Everything else is slow. Do they allow acetone in Cali?

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14 minutes ago, CaptainAhab said:

WTF kind of paint are you using? xylene & toulene are the fastest evaporating solvents. They use it in spray paint & carb cleaner. 
 

Acetone is very fast as well. Everything else is slow. Do they allow acetone in Cali?

Yeah - we can get Acetone. Paint is TotalBoat 2- or -1 pack primer. They say it's not for Aluminum, but I already sprayed Zinc Chromate on it, so the paint won't see any Aluminum, only Zinc Chromate.

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Which paint primer are you using?

https://www.totalboat.com/product/2-part-epoxy-primer/
Thinning: TotalBoat Epoxy Primer Thinner 200 

https://www.totalboat.com/product/aluminum-boat-barrier-coat-primer/
Thinner/Reducer: TotalBoat Epoxy Primer Thinner 20

https://www.totalboat.com/product/clear-epoxy-primer/
Thinning: TotalBoat Epoxy Primer Thinner 200

And the Thinner 200 =

https://www.totalboat.com/wp-content/uploads/2020/04/520415_TotalBoat_Epoxy_Primer_Thinner_200_SDS.pdf

image.png.41e39153a0961ea98aff7c946549d907.png

So... I'd thin with isopropyl alcohol 10-15% if you can't get Xylene. Lots of paint strippers contain both xylene and toluene but maybe not in CA.

It's commonly used to thin epoxies but don't go nuts with the percentage.

 

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That's interesting. Awlgrip 545 spray reducer is alcohols, glycol, benzene, and butyl acetate. The brushing is only glycol.  

Don't worry...all of them are carcinogenic

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On 1/5/2022 at 3:21 PM, Zonker said:

Hmm, I think I'm missing what you're asking. The strop just replaces a bail.

The strop takes the mainsheet load into the boom. It's pretty much a vertical force with a bit sideways when the boom is way outboard. Not much horizontal force going into the mast. 

 

image.png.37ba2e68b3495387d6949427066a7deb.png

 

 

who makes your strops

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3 hours ago, Grande Mastere Dreade said:

who makes your strops

I'm going to try using a climbing sling. Someone else mentioned that climbing hardware does not have the longevity needed for sailing, but they are so cheap. Worth a try IMHO. Bluewater ropes does some beefy spectra slings with high breaking strain.

My main problem now is figuring out how to secure them to the boom (sliding). Options are to fashion something that jams in the bolt rope slot, or just screw something to the top of the boom. Thinking...

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2 minutes ago, Irrational 14 said:

1/4 Dyneema rope with eye splice at both ends for block attachment. Wrap around boom 5 times. Done and stays put.

Round rope does not have the "coolness" factor of a strop. Also, climbing slings come in pretty colors...

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I'm struggling with the spray pattern for the Total Boat primer. It says "thin up to 20%" - so I did that and it's pretty runny, but the spray gun seems to be failing to atomize the paint. I have to turn the flow right down to a small patch, which is more or less circular rather than a fan. I've been friggin with flow rates and air pressure, but my sense is that it just needs more thinning. Does "bad shit" happen if I go to say, 30%?

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You already did all that work before I saw this.

I had the same issue on my J/92 with the holes from the old rope vang bail (replaced with a QuickVang).  The holes were in a more sensitive spot and for the reasons Zonker stated above, I didn't want to have them welded.  Nan Hall sent me a couple Hall Spars stickers.  Covered the holes and it looked (mostly) like a new boom.  It held up fine for 16 years.  And I have two more stickers...

I hope your boys are doing well and still sailing.  3BF?

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1 hour ago, BobJ said:

You already did all that work before I saw this.

I had the same issue on my J/92 with the holes from the old rope vang bail (replaced with a QuickVang).  The holes were in a more sensitive spot and for the reasons Zonker stated above, I didn't want to have them welded.  Nan Hall sent me a couple Hall Spars stickers.  Covered the holes and it looked (mostly) like a new boom.  It held up fine for 16 years.  And I have two more stickers...

I hope your boys are doing well and still sailing.  3BF?

I think I broke them for sailing when we did the Farrallons a couple of years ago. We came in second, but it was "sporty" enough to need a reef on the way out (first time ever reefing the boat, quite an adventure), and I hurled over the back of the boat, which impressed them quite a bit. I think they decided that sailing is for idiots, plus they committed to football. Older one is going to Virginia Tech in the fall but they are pretty good and despite being a conference first team RB, I don't think he will get any snaps. He may come back to sailing when he settles down, wherever that ends up being. The younger one is also committed to football (he's 6'4" and 210 lbs at 16 years old, and still growing). Smart, enormous and excellent offensive line. Anyway, not good for foredeck any more.

Boat is at KKMI getting new topsides and bottom. I'm saving money doing the prod and boom myself - hence all the questions.  Won't be ready for 3BF.

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I remember trying to find a race shirt small enough for one of them!  That sounds great.  Maybe they'll meet girls who sail and then they'll be all over it.

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13 minutes ago, BobJ said:

I remember trying to find a race shirt small enough for one of them!  That sounds great.  Maybe they'll meet girls who sail and then they'll be all over it.

Yeah - that's one of my best memories - winning our class at the 3BF and sending the 6 year old up at the awards wearing an adult small shirt with the hem trailing along the floor. I'm pretty sure that when he said "clockwise" to the "which direction" question, he let slip that the only reason we won is because we went the wrong way so that we would not hit anyone at the start, and the wrong way paid that year. What folks didn't hear was what he announced when he returned to the back of the room: "I don't need to go sailing any more because I've mastered it". I snorted beer through my nose and needed help.

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I had to go back and look at some pictures but on my Elliott the webbing was pop-riveted to the mast on the top left and right sides.

image.png.b22fe3a8af58e72d9271a38ffd07660c.png

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This TotalBoat primer is hard as nails. I sprayed on 3 coats - not exactly "orange peel", more like "ploughed field", but hey-ho, I'll sand a bunch of it off anyway. Bad idea - it's really, really hard. I started with 380 grit wet, nope. Moved to some 220, nope. 160 wet is also hard going, but I don't want to go any coarser. Ideas?

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The single most common mistake people make in paint prep is to start with too fine a grade of paper.

80 is generally the finest I start with.

If I'm sanding filler I usually start with at least a scuff with 60 to break the surface.

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4 hours ago, Zonker said:

80. THEN 120 or 160.

Did you leave it cure for a few days before sanding?...

I left it 24 hours, but it's pretty cool outside and I did notice that it was leaving deposits on the paper. Anyway, now that the weekend's over it will have to wait for Saturday, so it will get a full 7 days of cure before I hit it with the grit next time. Maybe I can sand, blow some more over any fuckups or bare spots on Saturday and blow topcoat on Sunday.

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