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View Full Version : Boomkin on a double ender



Arko
05-25-2015, 04:09 PM
OK, I hope this doesnt sound too ridiculous. I really need to add a boomkin to get something resembling a proper sheeting angle to my mizzen. My boat is, as I said, a double ender and has larg-ish decks at both ends to which I could mount the inboard end of the boomkin. Now, here is the questionable part, I would need to pass it through the sheerstrake via what would end up being an approximately 1 7/8" x 5" long oval shaped opening in the rear of the port side sheerstrake. It would be right between two frameheads just below the inwale and just above the aft deck. It would angle from the port side, through the sheerstrake and back to the centerline of the boat, giving clearance for the rudder head to be put full over. I have on the mizzen a 6' long boom that is only 14" inboard of the sternpost so I need something to reach out there about 5'. The mizzen is only 30square feet though so there wont be much strain on a boomkin. Does this sound like it would be safe? Advisable? Wise? Stupid? Any other ideas if this is no Bueno?

Peerie Maa
05-25-2015, 04:20 PM
We need pictures. Could the bumpkin sit on top of the gunwale, clamped to the top of the inwale?
Otherwise your idea sounds OK. Fit a doubler chock between the frame heads, and a chock for the heel of the spar on a deck beam.

Bob Cleek
05-25-2015, 04:24 PM
As they say, "need pictures!" From your description, I can't imagine what you are trying to accomplish, actually. You have a boom end that's 14" inboard of the sternpost. What's the problem with that? Why do you need "about 5 feet" aft of that? (How big is the boat, anyway?) What did the designer design to begin with? Boomkins are generally intended to support backstays, not boom sheets. A good accidental jibe would quite possibly snap what you are contemplating like a toothpick unless it was strongly stayed. Sorry, but I just can't understand what it is you are trying to accomplish.

Peerie Maa
05-25-2015, 04:35 PM
As they say, "need pictures!" From your description, I can't imagine what you are trying to accomplish, actually. You have a boom end that's 14" inboard of the sternpost. What's the problem with that? Why do you need "about 5 feet" aft of that? (How big is the boat, anyway?) What did the designer design to begin with? Boomkins are generally intended to support backstays, not boom sheets. A good accidental jibe would quite possibly snap what you are contemplating like a toothpick unless it was strongly stayed. Sorry, but I just can't understand what it is you are trying to accomplish.

Bob, I think that the mast is 14" inboard, leaving 5 foot of boom outboard.

I think that this is what is being proposed.
https://lh5.googleusercontent.com/-6c6cZDkxhck/UhqwTgWUfzI/AAAAAAAADFU/EctYVZBjW2g/s800/100_1879.jpg

Arko
05-25-2015, 05:31 PM
Thanks Peerie, yes that's what I meant to say. Sorry, my bad on using the wrong word Bob and confusing you. Really, is it that confusing? Trying to get a decent sheeting angle for a mizzen? Wow. I thought I did a decent job wording it for everyone to understand. Think a bow sprit but for the ass end of the boat. How about that? By the way, its a little 30 sqft piece of sailcloth and with what I had in mind I really don't think there will be any catastrophic breakages, accidental jybes or no.
Peerie, yes I too thought of fixing it to the tops of the gunwales and even made a mock up and didn't like the looks of it. It would be a different set-up than what I have in mind with the single stick going through the sheerstrake. What I mocked up was two separate pieces of suitably sized stock, one on top of each gunwale going aft past the sternpost meeting at about 5' past it. There would be some steambending involved with that idea but if it would be stronger I wouldn't be totally against it. With what I want to do I think it would be more than strong enough for what it needs to do. There are a few sizable deckbeams (for an 18'boat) under the decks that I would use for anchoring the boomkin to, plus a block with a mortice in it for the tenon on the end of the boomkin to lock into. The set-up I had in mind is exactly as is shown in the picture. Whos boat is that?
Thanks for your opinion peerie.

Arko
05-25-2015, 05:35 PM
By the way, good advice about the doubler block between the frameheads.

BBSebens
05-26-2015, 01:25 AM
Most of the Sail & Oar™ double enders have a boomkin that goes through the sheer strake. Seems to work just fine.

Peerie Maa
05-26-2015, 02:17 AM
Here is one on top of the rail.
http://farm9.staticflickr.com/8223/8271005024_53ea13e886_z.jpg

The boat that I pictured is from this thread http://forum.woodenboat.com/showthread.php?150064-20-Sooty-Tern/page29

stromborg
05-26-2015, 09:23 AM
http://stromborg.smugmug.com/Boats/Eun-Mara/i-fb5N33m/0/L/20141021_114830-L.jpg

I'll be doing something like this for my boat in the next couple of weeks.

James McMullen
05-26-2015, 09:56 AM
If it ain't got that stinger, then it ain't no honey bee!

James McMullen
05-26-2015, 09:42 PM
I reinforced the sheerstrake where it's pierced with a doubler.

https://c4.staticflickr.com/8/7772/17953980638_848126a435_z.jpg (https://flic.kr/p/tmwQWj)

jsjpd1
05-26-2015, 10:00 PM
Which is lovely and probably completely unnecessary. Mine goes through the sheer strake without a doubler and the plank shows no wear after several years of sailing. But maybe we are looking at different plank thicknesses.

James McMullen
05-26-2015, 11:05 PM
Lovely is good enough justification for me, honestly. But I think it may have helped protect the boat from extra harm when my boomkin got shattered coming alongside the Coast Guard cutter.

jsjpd1
05-26-2015, 11:26 PM
Fair enough, that is hard duty.

Arko
05-27-2015, 02:07 PM
Thanks all for affirming my intended approach to this. It seemed alright to me but you never know. That's why I like to ask you guys. Lots of experience to draw on here. Thanks then for sharing with me.
Going to laminate the stick using some fine grained doug fir tonight. Its just a big, scarey step, cutting a hole in a boat hull. Im having a hell of a time boring the hole for the drain, it just scares me. Its just not right putting a hole in your boat. ;-)

Peerie Maa
05-27-2015, 05:14 PM
Its just a big, scarey step, cutting a hole in a boat hull. Im having a hell of a time boring the hole for the drain, it just scares me. Its just not right putting a hole in your boat. ;-)

It's an open boat. She has a huge hole in her top where you sit. ;)

Bob Cleek
05-28-2015, 03:37 PM
If that's all your about, then "What Peerie said!" :D

Jay Greer
05-28-2015, 08:03 PM
Have you considered placing the lead to the head of your rudder stock? This would eliminate the need of any holes in the hull. "Jiggers", Mizzens, don't need to be strapped down too tight as they don't come into play until the boat is slightly off the wind. Take a look at the mizzen leads of the ketches and yawls designed by L. Francis Herreshoff before you cut that hole.
Jay

James McMullen
05-28-2015, 09:54 PM
I'm afraid I have to disagree with you, Jay. I tried the actual experiment using the exact same boat both with the mizzen sheeted to the rudderhead, and then sheeted to a boomkin. I thought the boomkin was better in every single way. When I built Rowan later, I never even considered not having a boomkin. In my opinion, it's way better with.

BBSebens
05-29-2015, 12:39 AM
Have you considered placing the lead to the head of your rudder stock? This would eliminate the need of any holes in the hull. "Jiggers", Mizzens, don't need to be strapped down too tight as they don't come into play until the boat is slightly off the wind. Take a look at the mizzen leads of the ketches and yawls designed by L. Francis Herreshoff before you cut that hole.
Jay


I'm afraid I have to disagree with you, Jay. I tried the actual experiment using the exact same boat both with the mizzen sheeted to the rudderhead, and then sheeted to a boomkin. I thought the boomkin was better in every single way. When I built Rowan later, I never even considered not having a boomkin. In my opinion, it's way better with.

I suspect this is a difference between large and small craft. Many larger yawls seem to manage just fine without boomkins, having mizzens set a bit farther forward, whereas smaller yawls need every inch aft afforded by a boomkin.

Eric Hvalsoe
05-29-2015, 01:05 AM
Here is one on top of the rail.
http://farm9.staticflickr.com/8223/8271005024_53ea13e886_z.jpg

The boat that I pictured is from this thread http://forum.woodenboat.com/showthread.php?150064-20-Sooty-Tern/page29

That's me. HV16 Bandwagon. Content not to have pierced the transom. Plenty other folks do - pierce the transom or sheerstrake. This is a tiny mizzen.
Eric

Ben Fuller
05-29-2015, 07:35 AM
On RanTan I also have the boomkin on top of the rail. I have a bit of wood that some bolts with wingnuts hold onto the small after deck that sticks out far enough to catch the boomkin. It has the added benefit of having a spot onto which to mount an oarlock socket inboard of the boomkin so I can scull. This is pretty much what the various surfboats and whaleboats did to mount their steering/ sculling oar. I just ran it out a bit further to take the boomkin. All of this was put together after the boat was together and the rig installed so that the boomkin end was where it need to be and the lashing point on the inboard side was set positioned right.

Jay Greer
05-29-2015, 01:13 PM
I'm afraid I have to disagree with you, Jay. I tried the actual experiment using the exact same boat both with the mizzen sheeted to the rudderhead, and then sheeted to a boomkin. I thought the boomkin was better in every single way. When I built Rowan later, I never even considered not having a boomkin. In my opinion, it's way better with.
Jay[/QUOTE]
The reason I recommended you to look at Herreshoff mizzen sheeting to the rudder stock was so that you might see a means of gaining an advantage by not needing to take the bitter end of the sheet attachment to the boom further aft than necessary. Often this point can be of advantage at a point between 3/4 to 7/8ths of the length of the boom. This still allows leverage for sheet control while being much simpler to rig. In fact it can also, in effect act as a semi vang or to flatten the jigger with a greater downward pull than end of the boom attachment will. This is why many top racing boats sheet their mains from points other than the bitter end of their booms. In doing so the set up is simpler as well as more rigid as it offers a point of attachment that does not spring up in gusts unless, a boomkin bobstay is used. Boomkins have a maddeningly nasty habit of getting in the way at the wrong time as well as ending up being broken. Certainly you are the best judge of how to rig your own boat. It looks like you are doing the right thing by trying all solutions before making a final choice.
Jay

Arko
05-30-2015, 11:08 AM
It's an open boat. She has a huge hole in her top where you sit. ;)

But not in the bottom

James McMullen
05-30-2015, 11:09 AM
Yeah, yeah, but you're putting the new hole in the side. What could possibly go wrong?

Arko
05-30-2015, 11:12 AM
I did Jay but decided against it. The boomkin just seems to be the best option for this but thanks for your insight and taking time to answer.

Arko
05-30-2015, 11:14 AM
Yeah, yeah, but you're putting the new hole in the side. What could possibly go wrong?
Far above the waterline. Besides my saying all that about the hole in the boat was just sort of said in a joking manner, although is really isn't right putting more holes in your boat.

James McMullen
05-30-2015, 11:28 AM
Aw shucks. I done put plenty of holes in my boats and rarely, if ever, sink from any of them. Putting more holes in yer boats offers you the satisfaction of getting to do a new project. And who wouldn't like that?