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Date Posted: - Tuesday - 08/27/13 - 1:18am
Author: Randall, Murre, M31
Subject: lamination vs solid
In reply to: andrew bradley 's message, "bow sprit / haws holes" on - Sunday - 08/25/13 - 7:52pm

I replaced my laminated Sitka Spruce sprit with a solid piece of Doug Fir in 2010 (old one was succumbing to rot). The Fir is heavier that the Spruce by a few pounds but lighter than the hardwoods by a lot. Not sure why one would go with hardwood due to its weight at the bow (maybe this is a bigger issue with the 31s than the 40s?), and fir is easily sourced. Also advantage of laminated seems nominal in my opinion. I really don't get why the original sprits were laminated. I've got 12,000 miles on the Fir sprit with no problems.

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Replies:

[> [> Warping? -- Paul, - Wednesday - 08/28/13 - 7:42pm

When I built mast, boom, gaff and bow sprit from clear fur when I built my Friendship sloop, I ripped each lenght of wood used to build each piece in half, flipped one side and glued the pieces back together to offset any and alll tendency to bend, twist or warp. They stayed perfect for better than ten years as I used the boat, until I donated her to the Seascouts.

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[> [> [> Tight Grain -- Gitano, - Thursday - 08/29/13 - 2:30pm

Wood selection is key! The fir used to build the new bowsprits for Randall and I are nice tight grained fir, and thus somewhat prone to warping. Also the wood was not green, but was cured properly. One other thing, once the sprit was cut and shaped, it was sealed with wood sealer or varnish all around. This is not such a concern in our case since the wood used was cured before being shaped into the sprit, but if using green wood, or wood that is not completely cured, it can dry unevenly if not properly sealed, and WILL warp under this condition.

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[> [> [> [> bow sprit -- andrew, - Monday - 09/ 2/13 - 1:07pm

Thanks guys for your input.
This is going to be a winter project I think.
After talking to a number of people and taking in all the advice, I will be building the sprit out of Douglas Fir for price, availability and strength and laminating it.
But I do have another stupid question....
My father in law seems to think that each laminate needs to be fastened together with either stainless or bronze screws as well as epoxy.
I've seen this in the building industry but I haven't seen anyone mention this on any of the forums regarding the construction of a sprit.
Is this simply common sense or does one NOT fasten the laminates together ?
Personally I would think this necessary keeping in mind the enormous loads placed upon a sprit to keep up a deck stepped rig.
I've yet to scrape off the paint to see how they built mine.

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[> [> [> [> [> sprit -- andrew, - Monday - 09/ 2/13 - 1:40pm

I will also probably use West System epoxy.
I understand that I should flip the laminates end for end for opposite grain and whether or not I screw the laminates together or simply clamp them, not to do so too tightly as to starve the join of epoxy.
Then I am to understand to shape and soak the sprit in thinned epoxy before sanding and painting.
I'm motivated to do this myself after the ridiculous $7000 quote I received from Canoe Cove that didn't include the removal or installation .
They do great work but c'mon !!!

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[> [> [> [> [> [> sprit -- andrew, - Monday - 09/ 2/13 - 1:48pm

One last thought........I've been advised to use naturally dried wood instead of kiln dried.
I'm told that the kiln dried is somewhat more brittle than the naturally dried product.
I'm also wondering if anyone knows if the sprit is notched into the samson post or uses a dowel of some sort to attach it to the post

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[> [> [> [> [> [> [> Naturally Cured - no fasteners required -- Gitano, - Tuesday - 09/ 3/13 - 12:09pm

Yes, Andrew, naturally dried is definitely preferred. Both Randall's and my spris were built from naturally cured tight grained fir - probably both from the same tree. I don't know why one would need fasteners for the lamination. Just use lots of clamps, in both dimensions. The epoxy laminate would be stronger than any fastened sections of wood. Fasteners will create weak links in the system, in my humble opinion.
Best regards,

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[> [> [> [> [> Fasteners and fitting to samson posts -- Randall, - Tuesday - 09/ 3/13 - 12:19am

Hey Andrew,

I remember Annie Hill talking about constructing the hull of BADGER out of plywood and epoxy. They would use fasteners to fit the pieces in place and hold all together while the epoxy set, and then when set, they'd remove the fasteners because they weren't necessary and they could then use them somewhere else. They were extremely frugal, she and her husband. BADGER spent time in the southern ocean, so I guess she was strong enough.

Regarding the fit of the sprit to the Samson posts, see my post on replacing Murre's bow sprit. I assume the 40 and the 31 have a similar set up. The sprit is notched to butt up against the posts AND a cap block on the deck. See the drawings in particular.

http://www.marineryachts.com/projects/murre/bowsprit/Bowsprit%20Installation.htm

On Murre there's a 5/16ths through bolt that passes through both the Samson post and the sprit and anchors it in place (when replaced I went to 3/8ths). There was also a long bolt through the sprit and down through the deck that I did not replace. Didn't find it necessary. This bolt had an eye on top that was used for the storm jib, but I moved this eye to the side deck. Much of the rot in the sprit was at this point.

Another neat trick from Bruce on Gitana Vella. Drill out the fitting holes double large and fill with epoxy. Then drill for your fasteners. Good rot protection. Again, see my post.

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[> [> [> [> [> [> sprit -- andrew, - Tuesday - 09/ 3/13 - 9:56pm

Well thanks again for the comments.
I must say that its hard to believe that epoxy alone will be strong enough to keep it all together under all those loads but I guess it works.
Having said that, it is the joins that have caused the problems where water has got in and migrated up and down and began rotting.
But I think that it is the original so i guess that that's pretty good for a 40+ year old boat.
If I can post some photos, I will of the damage.
Then I will chronicle the rebuild.

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