Putting cleats on the CB trunk

Moderator: GreenLake

Re: Putting cleats on the CB trunk

Postby DigitalMechanic » Tue Jan 16, 2018 9:48 pm

I doubt those cleats are coming out of the CB trunk. The fiberglass is at least 1/2" thick there. Pretty beefy, and the cleats assume up to some 300lbs of load, and I doubt that 41.4 Sq ft of foresail can produce that much force on the cleat past what is shared with the the blocks. I guess anything can happen in the right amount of wind, but the main point is that the fiberglass is stronger than the cleats and blocks. One of them would break first.

I agree the angle is not 100% ideal coming into the fairleads. The bullseye fairleads do not care much about that though. They line things up right in front of the cleat. Your "Wire loop" should perform a similar function, but maybe not at as tight of a tolerance. After sailing in other boats, and dealing with foresails on similar sized boats, I kind of wish I had thwarts... Would make things a tad more tidy of the jib sheet cleats were there.

At any rate, I like the setup. Yours should make the boat a lot more fun to sail. I remember when the jib sheet cleated off on the opposite coaming of my boat. It required nothing short of a "round house" kick in any decent amount of wind... to cleat or un-cleat. It just plain sucked, and there were scary moments where I crossed an already over powered boat to try and get the damn thing loose :shock:
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Re: Putting cleats on the CB trunk

Postby GreenLake » Tue Jan 16, 2018 10:23 pm

I've sailed on boats where the sheets are cleated next to the crew sitting on the rail. Generally works really well with these caveats: don't forget to uncleat before changing sides, works best if crew is always on the upwind side, may be a bit less convenient in very light air sailing or when singlehanded (not that you'd want to sail those boats single handed...).

A bit difficult to implement on a DS1 where you have no good place to put an upwind cleat (unless you have cut your coamings flush you may have to build a platform outside the coaming), however it is worth mentioning for completeness. If you end up sailing fully hiked out all the time, you'll find that setup even easier than the best cleats on the center line. And of course, for boats with a trapeze there's no choice.

(Has anybody ever put a trapeze on a DS - for fun, not racing as it's not class legal, of course - answer in a separate topic).
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Re: Putting cleats on the CB trunk

Postby MookaCB » Wed Jan 17, 2018 5:40 pm

Here is the way mine is set up. The cleats are screwed into the CB truck with 2-2 1/2 inch stainless screws. I don't recall any metal backers, but it has been a couple years since I replaced those cleats.

I have raced and sailed her pretty hard without ratchet blocks on my jib sheets and they haven't ever come loose.
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Re: Putting cleats on the CB trunk

Postby GreenLake » Wed Jan 17, 2018 11:40 pm

About how to estimate maximally possible forces on sheets:

A nifty realization is that the if the wind force on the sails becomes too strong, then the boat will capsize. Therefore, the system has a built-in cap on how much force the rigging will have to withstand, and that cap is defined not by the wind, but by the righting moment that the strongest wind would have to overcome to capsize the boat. That moment is easily estimated by calculating the product of the mass (ballast = crew while hiking) times the lever arm (distance of center of gravity from approx. centerline). Good enough for a rough calculation. To get the force on the sail, divide by the distance of the center of effort (usually the bottom third of the sail) to about the waterline (again not the exact value, but an approximate location).

The maximal forces on an individual sheet will be in the same order of magnitude, and you'll probably find that by the time that they would hypothetically reach 300#, the boat has capsized long ago... (I'll let someone else try to make a detailed estimate).

The one exception to this are shock loads. The mainsheet may be subject to those, in case of an uncontrolled gybe. As a result, it might be useful to allow for a bit larger safety factor when estimating the fittings for the main sheet.
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Re: Putting cleats on the CB trunk

Postby DigitalMechanic » Thu Jan 18, 2018 9:37 am

I had an accidental Gybe the other weekend. Took 2 new sailors out (well one is in the Navy, but never been on a sailboat, the other was his son). At any rate, there was a breeze, and I kept mentioning the importance of "weight management". I do not think that they were taking me to seriously until after we had a bad gybe (we planned on doing a gybe, but occurred prematurely). I caught the part of the sheet attached to the boom with my hand as the mainsail went shooting across the boat (I usually hold it anyway on a tack or gybe), which helped with "rigging shock", but with enough wind and me stretching, the boat still went nearly over. They immediately jumped to my side of the boat, lol. I stopped the youngest one half way across and told him to wait for a second (did not want the boat to heel back to windward on the rebound and go over). Upside down pendulum, lol. Our tacks/gybes seemed to miraculously improve after that :D

At any rate we are all going to have a bad gybe at some point. I imagine to much shock could easily crack the gelcoat (that any block is attached to), but I would be shocked if the fiberglass in that particular location actually failed (unless something else was already going wrong with it). You should capsize, but the daysailer's boom is relatively high on the mast, so it heels quite a bit before you get in trouble. I think I came close to capsizing the boat once. It felt like it was about to go over it suddenly "snapped" into a roundup? It happened quick. Maybe I panicked and released the tiller? It felt like it was nearly a 360 degree sliding turn in a split second. Have not done it since, and hope I never do again, lol.
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Re: Putting cleats on the CB trunk

Postby badnews » Thu Jan 18, 2018 12:22 pm

Heel the boat far enough and as the rudder approaches horizontal it progressively loses its ability to steer the boat. This is probably what caused you to round up so violently without any apparent feedback through the tiller. I would say that qualifies as "close to capsizing".

For my setup, I'm not particularly worried about tearing the cleats off the centerboard trunk with the load generated by the sheets. Even in the most violent circumstances it would be hard to shock load a jib sheet that significantly, and as Green Lake points out there's just not enough sail or enough boat involved to do it without a big shock. I could see one being damaged by impact (people falling, loading or unloading things from the boat, etc), as they do stick up more than if they were screwed straight to the centerboard trunk. I think it would likely just break the cleat and not tear it free though.

Mooka, is the wood block in your install just a spacer or riser?
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Re: Putting cleats on the CB trunk

Postby GreenLake » Thu Jan 18, 2018 2:31 pm

I've experienced several of these "violent rounding ups", where the boat effectively twists out from under a gust. I tend to think of them as a safety valve. Had the rounding up not happened, the boat would most likely have responded by capsizing. Only if there's enough weight on the rail would it have had a chance to translate the increased wind power into an acceleration.

The rounding up is a result of the center of effort moving aft, so that it can push the boat around the center of lateral resistance. That implies that the contribution from the main suddenly dominates that from the jib. The boat does start to heel initially, and then the rudder loses grip, allowing the boat to turn to weather. I wonder whether this may not be a combination of reduced projected rudder surface (due to heeling) but also an actual stalling of the rudder foil - where the rudder loses attached flow and becomes ineffective.

It's been a while that any of these have happened to me. I may have become much quicker in responding to gusts by letting out some main sheet; with a ratchet block I tend to cleat the mainsheet much less. I did upgrade to a different rudder, with a foil shape, that while not perfect, at least approximates some useful profile - this may make the rudder more effective/less prone to stalling.

If it was just the latter, I should have experienced more "near capsizes" (without rounding up) but I don't recall that.

One factor that I observed is that sailing near tall structures (bridges) or bluffs/hills seems to make these events more likely, as a falling gust can come out of any direction as it spreads on the water, thus hitting the sails in ways that they are not trimmed for at the moment. I now look for those conditions and tend to be extra cautious.
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Re: Putting cleats on the CB trunk

Postby UffdaFox » Tue Mar 20, 2018 12:03 pm

I have a DSI that has no provision for jib cleats on the CB trunk. When I purchased the boat, the cleats were held with machine screws directly into the top of the trunk and this obviously didn't hold up to regular use. I rigged a temporary solution anchoring through the bench to the bracket beneath (glassed into the sides of the CB trunk to support the benches). Trying to avoid adage "there is nothing more permanent than a temporary solution" and do something a little nicer looking and longer-lasting. My initial thought is to place a piece of mahogany a bit wider than the CB trunk along the top of the trunk (running with the trunk) and then use some sort of bracket with small carriage bolts through the very top of the CB trunk.

Thoughts on that solution?
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Re: Putting cleats on the CB trunk

Postby GreenLake » Tue Mar 20, 2018 2:25 pm

Previous owner used aluminum U channel; after some decade(s) this corroded. I replaced with SS that I had machined. Looks like new after a dozen seasons...
712
It was not expensive, looked better than anything I would have done, and, not being made of wood, needs no maintenance.

Held by horizontal through-bolts that pierce the CB trunk immediately below the top (as you look up the inside, they are visible as they cross the CB trunk, but they don't really protrude into the space and never make contact with the board.
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Re: Putting cleats on the CB trunk

Postby UffdaFox » Wed Mar 21, 2018 11:59 am

Thanks, that's exactly what I am looking for. Would you mind sharing measurements for your bracket and where you attached to CB trunk? Also, did this require sealing to prevent water from getting in?
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Re: Putting cleats on the CB trunk

Postby GreenLake » Wed Mar 21, 2018 6:10 pm

You can see the attachment bolts in the picture.

The width is precisely that of the CB trunk. There's a bit of a corner to fit it; I think the PO took an angle grinder and ground that out (the corner isn't very deep, so no fear that it will go through all the way - the laminate is pretty substantial.

If you think of the top of the CB trunk as an inverted U, the bolts are placed such that they are just inside the curved portion of the U. From the Photo, you can see how that relates to the external curve. The size of the bolt heads also gives you a clue.

Now, the height above the CB trunk is governed by the need to fit the bolts for the cleats (those only attach to the SS bracket, not the CB).

On my boat, the top of the CB was raised a bit at that location; I had to drill a shallow depression or two to make room for the nuts; not sure whether this raised part was factory original or add-on by some PO. But I may have a different year DS than you.

Not least for that reason, you'll want to take your own measurements. (The part on my boat is about 9" long, 1.5" across and 1.25" tall and made from what appears to be 1/16" sheet metal - I think the shop bent it themselves instead of using any standard channel stock).

The length fore and aft was chosen to match the previous part that had been on the boat; you can see that there are some additional holes - some owner must have had larger cleats with a different hole pattern, and when the machine shop reproduced the part, they simply drilled all the holes as they found them.
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Re: Putting cleats on the CB trunk

Postby UffdaFox » Sat Mar 24, 2018 11:03 am

Thanks, GreenLake. Can you point me to painting water lines and bottom paint in the forum?
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Re: Putting cleats on the CB trunk

Postby GreenLake » Tue Mar 27, 2018 2:39 am

There are suggestions how to use external search engines to search the forum; look in the "how to" section.
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