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Old 15-03-2017, 18:56   #1
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Anyone have a boomkin and any advice on building one.

Hello all I posted this in the rigging section and got no bites...I would also like to say thank you for all the responses I've gotten thus Faron my other topics, so here's where I'm at ; I'm pulling the mast and replaceing the standing rigging. So far I have all the upper and lower shrous material and have a plan formulated, as to what I'm going to be doing. (replacing upper and lower tangs, upping wire sizes,fabricating bronze chainplates to the hull sides,bronze toggles and bronze turn buckles [is there a reason there isn't 3/8 bronze Clevis pins?].) which leads me to my boomkin,which is currently 2x3 solid wood and my back stay is attached to it. I'll be fabricating/welding a new one. I've decided on going with of 304l( if I cant find it in 316l) sch 40 ss pipe which is 1 1/2" od x .120 wall x 1.26 Id. Which leads me to the question the stays that go under the boomkin, what are they called? And is there a reason to use stays rather then hard pipe? I assume the stays are better to prevent shock loading? Is this the only reason? Gathering the materials to build the new boomkin and trying to decide wether to replace the stays with pipe or to build new wire stays.Thanks
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Old 16-03-2017, 01:22   #2
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Re: anyone have a boomkin and any advice on building one.

EH24, I find that I'm wondering why you are feeling the need to massively upgrade t he sizes of all this rigging and other hardware? I'm not really familiar with your boat, but I had the idea that they were well regarded. Have you some info that says their rigs are failing due to undersized components? And have the timber boomkins been folding up under load?

I keep getting the feeling that you, in an effort to improve the design are really degrading it by adding weight aloft, windage and generally messing with a successful design.

And really, a stainless clevis pin will surely suit your needs, but if you simply must have bronze, rod of the correct diameter and with a split pin at both ends rather than just one will work as well as a "real" clevis pin.

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Old 16-03-2017, 01:54   #3
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Re: anyone have a boomkin and any advice on building one.

I'm in concurrance with what Jim said. With the addendum that if you want to improve things, you could:
- remove your current boomkin, & wrap it with glass, prior to recoating it with the UV protectvie finish of your choice. And oversize all of the holes & penetrations in it, fill them with epoxy/thickened resin, & then refasten & reinstall it.
- Switch to rod rigging for your boomkin's stays, ditto on your dolphin stryker. As rod's a lot more corrosion resistant than rigging wire, & also, water can't get inside of it as is possible with wire.

Also, you should be able to source some gratis, from any racer doing a rerig, or from a rigging shop. Just use the middle part of any sufficiently sized stay. As it's the ends of rigging that get work hardened, & wear out.

Rod's nice in that it's made from Aquament (Nitronic 50), which is super corrosion resistant, & super strong. Plus if you use some off cuts as suggested, finding some that's grossly overstrength will be quite easy.
Rod's sized by breaking strength, so -17 has a minimal strength of 17,000lbs, while being all of 0.33" diameter.
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Old 16-03-2017, 08:06   #4
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Re: anyone have a boomkin and any advice on building one.

I considered the idea of wrapping the current boomkin with glass. However I couldn't find much about it. That's what I would like to do, I wasn't to sure of the process
. I was thinking of laminating some dougfir then wrapping with glass. But figured the stainless will be stronger lighter and less worrisome.The reason I'm beefing everything up is ; while I haven't heard of any eh rig failures or boomkins buckleing etc , but then again I haven't heard any first hand experiences wth this boat. However im planning to do some cruising in this boat offshore, and piece of mind is a plus. My rig was designed for a small self tacker and I now have a 150 genoa on it. It handles it very well, I keep it all the way out a lot and really pushes the boat. I've since managed to crack the welds on my setemhead fitting and just about pulled my deck mounted chainplates through the deck. So I've decided to repleace everything move the chainplates to the hull sides, and bump all wires up one. Also I'll be adding a Solent stay, running with 2 headsails will be an option . So I would like to be sure my boomkin can take the loads . I'm rolling the dice as far as the windage and weight aloft that the piece of mind and extra strength won't hamper things too much.Also the added stresses of a self steering rig on the boomkin (down the road). I already have most of the material so I'm pretty much all in at this point.
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Old 16-03-2017, 08:15   #5
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Re: anyone have a boomkin and any advice on building one.

Understood. Though when it comes to beefing up rigging, it can be overdone. Since the beefier rigging requires that each shroud & stay be tuned to a higher loading, than if it were the original size, so that the rig properly stays in column, & your stays aren't too loose. Which, this can add a LOT of extra compression to the mast tube, as well as downward force on your mast step, & keel. Along with the equivalent upwards pull on all of your chainplates.


Might want to do the math on this first, prior to making all new stays & tangs. As well as running it by a rigger or rig designer. Since turning the boat into a banana can have permanent ill effects. Ditto in terms of what it can do to one's wallet.
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Old 16-03-2017, 08:43   #6
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Re: anyone have a boomkin and any advice on building one.

My compression post goes Down to the lead that's encapsulated in the keel. I've considered that, but shame on me not as much as I should have.I'm thinking with the compression post sitting directly on the keel things should be ok in that dept. heres a pic of my boomkin...I was also kicking around the idea of clearing off the deck by mounting the boomkin "off" the stern, rather then "on top". I understand with it on top the compression strength is increased with the length of the wood. Since the ss will be stronger I was debating clearing it off the deck and just butting it up to the stern. Forgive me for the poor description I hope you understand the picture I'm trying to paint. As far as the bronze clevis pins I was just wondering since everything is bronze and I know enough that keeping similar metals is usually the goal why are bronze clevis pins so rare? The Assumption is since bronze and ss are so close on the galvanic scale, and ss is slightly stronger?
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Old 16-03-2017, 08:45   #7
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Re: anyone have a boomkin and any advice on building one.

I agree with Jim, in that you will compromise the sailing ability of your boat with all of the excess. I dont know the Eastward Ho, but they seem to have a good reputation. There should be no reason in the world for a well designed boat to have chainplates pulling out. This sounds very wrong and I would recommend that you invest the money in a good surveyor or rigger to tell you why this is happening. I had an early Contessa 26 with deck mounted chainplates and beat the stuffings out of that boat for years, including 6 days under double reefed main and storm jib, close hauled in the trades. Absolutely no strength problems at all. Is there an Eastward Ho facebook group? Maybe the Eastward Ho is more like a Venture with more teak and should not be in the open ocean? It all sounds wrong. Money spent on a surveyor or rigger will probably save you money in the long run and make your boat better. I wish you luck. ____Grant.
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Old 16-03-2017, 08:54   #8
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Re: anyone have a boomkin and any advice on building one.

I don't see any problem with using pipe instead of cable for the boomkin support. Cable might be a lot easier though.... getting the end angles perfect is always a challenge in fabricating a pipe assembly. You could use rod with end fittings instead of cable.
Not sure why you don't see too many bronze pins, but likely just because the mix of Bronze and SS has always worked out well and SS readily available.
I'm with the others, unless your rig is under designed, leave the wire sizes as they are. 20# of extra weight 20 ft up is like losing 400# of ballast.
I think we all have made the mistake of trying to "make it better" when it was not needed.
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Old 16-03-2017, 09:01   #9
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Re: anyone have a boomkin and any advice on building one.

Hi Eastward, I don’t have nearly the knowledge or experience of the responders so far, but I do have a boat which has had her teak boomkin replaced with very hefty stainless steel tubing.

I don’t know what (if any) improvement this change made to the overall strength of the rig, although I strongly suspect it has. Our boomkin has those lower stays (? not sure what they’re called either) that attach below the boomkin. Ours are the same ss rigging as the backstay, and attached via turnbuckles and chainplates.

Anyway, I’m not sure if I can be of any assistance, but our boat’s conversion seems similar to what you’re suggesting. Although our boats are quite different...
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Old 16-03-2017, 09:09   #10
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Re: anyone have a boomkin and any advice on building one.

Yes maybe I should leave the wire sizes the same. I know the Dana 24 uses the same sizes I currently have. Didn't realize that 20# up 20' would detract that much. I guess it's better I keep the wires the same especially since I've added a annomometer wind point (signet) and vhf at the mast head and I'll be putting a radar dome half way up..add that and my double tangs bigger wires etc. I guess I will be getting into some diminishing returns..haha any one need some dyer double tangs 3/8 pins.. I think I'll keep the sizes and still beef up my boomkin though.
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Old 16-03-2017, 09:11   #11
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Re: anyone have a boomkin and any advice on building one.

Thanks mike . Do you have any idea what size stainless you used?
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Old 16-03-2017, 09:54   #12
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Re: anyone have a boomkin and any advice on building one.

A solid pipe support for your boomkin is easier and cheaper to fab than a wire one. Wire requires a mounting tab on the boomkin, the wire, end fittings and a turnbuckle. The pipe just needs the pipe. Fit your pieces of pipe and their mounting plates that will bolt to the hull. Bolt the plates to the hull. Lightly tack weld the pipes to the mounting plates and to each other. Then remove the assembly and finish weld. This ensures all the angles are correct. Shock absorption of the wire is a non issue.
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Old 16-03-2017, 09:59   #13
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Re: anyone have a boomkin and any advice on building one.

I can weld stainless so I will be able to fab my own boomkin. "Shock loading is a non issue", I wonder why so may boomkins use the wires instead...ahh now to stop the urge to up the wire sizes and pin sizes. Just feels so right..but as you all have mentioned just isn't worth it I guess. Actually gonna make this a lot easier.
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Old 16-03-2017, 10:30   #14
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Re: anyone have a boomkin and any advice on building one.

Quote:
Originally Posted by Eastward ho 24 View Post
Thanks mike . Do you have any idea what size stainless you used?
Unfortunately no, and I’m not close to my boat to get a measure. The work was done by a previous owner. Here’s some pics though. Perhaps you can gleam something useful from them:
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Old 16-03-2017, 10:47   #15
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Re: anyone have a boomkin and any advice on building one.

I'm going to take the opposite tack... What's wrong with a wood boomkin? I have a wood wishbone shaped boomkin on my 44' ketch made from laminated sitka spruce, each arm is about 2"x4" extending 30" from the transom. Strong enough to walk on and easier on the feet than pipe, looks nicer too but that's subjective. I do have the lower stay (stern bobstay?) of 3/8 wire and a turnbuckle. When loaded the boomkin is in compression and the bobstay and backstay are in tension, no need to support the boomkin end with a pipe.
Was your boat originally designed with a boomkin? If so then you should have the proper fittings. Does the boomkin flex? If so you can make one out of pipe but don't discount wood, just a bit beefier but keep to the original design. BTW the quickest way I know to rot a piece of wood is to wrap it in plastic or fiberglass.
Just my $.02.
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