Building a bowsprit

[Epoxybreath]

Hey folks'
I've just been asked to build a bowsprit for a cutter rigged 31' footer. Seems the old one has seen better days. I'll be using black locust as a medium. The sprit will be almost six feet long and the butt is roughly five and a half inches square. I would like some feedback as to the wisdom of laminating vs. using a solid timber. And perhaps a few comments on air dried vs. kiln dried for this application. Here is a link to a photo a similar bowsprit. Thanks and a tip of the hat, Bruce

http://home.comcast.net/~independence31/bowsprit.jpg

[Epoxybreath]

[JimConlin]

Had you considered a lighter material than black locust? Douglas fir, perhaps?

[pcford]

I recently did a bowsprit for a little Garden cutter. Used air-dried fir. $13BF from Olsen's/Dunn here in Seattle. Beautiful stuff...wood like they have in heaven.

Roughed it out to four sides...then eight sided the stick with drawknife, rounded it with planes and finally sanded it.

Bowsprits are fun...get to make the chips fly. I am dubious about the locust...sounds like it is not a friendly wood to work with. But I don't know.

[David G]

E'breath,

First, let's get the species straight. People sometimes confuse two very different species.

First - what's frequently called "black locust" in the US is Robinia pseudoacacia. It's not black at all in appearance, but rather, more straw-colored, along the lines of a light luan, or an occoume. It's relatively light in weight also. EDITED to add: light, that is, when compared to the second "locust."

Second - what's most commonly called "West Indian locust" in the US is Hymenaea courbaril. It's sometimes also called locust or black locust. It's much darker and much heavier.

Given the strength required of typical bowsprit, and the added strength required of a cutter rig, I'd be leery of the former species. The latter, while much stronger, may be more weight than is necessary or desirable.

What species is the existing sprit? Did it fail from extraordinary trauma? Rot brought on by maintainance issues? Or because the sprit was not strong enough from the beginning?

As always - the devil's in the details. The more relevant info you provide, the better advice the folks here can offer. Just as a wild example: does the owner make a regular habit of cruising in the Roaring 40's? Or... is it against his religion to put in a reef?

[JimConlin]

E'breath,

First, let's get the species straight. People sometimes confuse two very different species.

First - what's frequently called "black locust" in the US is Robinia pseudoacacia. It's not black at all in appearance, but rather, more straw-colored, along the lines of a light luan, or an occoume. It's relatively light in weight also.
...

According to the USDA/FPL Wood Handbook, Black locust has a specific gravity of .69 (12% m.c.).
http://www.fpl.fs.fed.us/documnts/fp...tr113/ch04.pdf

Lovely stuff for tillers, rub rails and cleats. Distinctly not light weight.

[paladin]

You can obtain very nice fir, sold as stair tread stock, almost anywhere around Silver Spring. Slice it edge wise down the middle and reverse the one side and epoxy it back together.....use three such pieces insuring that the grain is alternated and it will be as good as quarter sawn stock...better perhaps...make at least 6 laminations for the total thickness required.....then make your sprit.

[johngsandusky]

I replaced a rotted spruce bowsprit with juniper. Old and new were both solid. I used the juniper because I could get it, but not good spruce or white pine at a sane price. I figured that a 4x6" peice of even softwood would be fine with stays. I was right, it's still sound after some hard use.

[David G]

According to the USDA/FPL Wood Handbook, Black locust has a specific gravity of .69 (12% m.c.).
http://www.fpl.fs.fed.us/documnts/fp...tr113/ch04.pdf

Lovely stuff for tillers, rub rails and cleats. Distinctly not light weight.

You're right - I was unclear. I was trying to say it is light relative to the courbaril... which has a specific gravity of about 0.90. I'll edit it to make that distinction.

For comparison purposes, the douglas fir which has been recommended by several has a s.g. of about 0.52, IIRC.

My concerns remain, however, about pseudoacacia as a suitable material for a bowsprit. Not only is it only medium strength, it is low in both stiffness (which would be important when it comes time to tighten up the forestays) and resistance to shock loads (like smacking it into a dock, etc.). It also has a tendency to warp or twist in larger pieces (like a spirit, as opposed to a cleat). In addition, it has a marked tendency to discolor when in contact with iron/steel (like a cranse iron). And, finally, it is quite coarse textured which makes it more of a challenge to keep varnish on (which sounds as if it may perhaps have been the root cause of the demise of the former sprit).

As a general thing, the doug. fir would be typically more suitable. But we haven't heard any more detail form the OP yet, so I'll hold off on a conclusion.

[rob]

David G, I think you need to do a bit more comparisons or recheck your tables. Black locust is just about the strongest wood that grows in north america...far exceeding the requirements of a bowsprit...for which spruce or fir are much better choices to reduce wieght and also it has very high shock resistance, you simply cannot break a locust adze or ax handle. Yes it does darken with iron, but so will any high acid hardwood (cherry,oak,mahog....) In terms of stiffness, I would need to go back to the tables myself...but I thik a piece of dry locust is pretty darn stiff. I will certainly agree that it's tendency to move is pretty strong....mostly when fresh cut or intially drying...once the stress is out it settles down quite nicely.
To adress the original post, I have never seen a hardwood bowsprit. You don't need that much strength, you don't want that much wieght, and it would be a chore to fashion. Get some nice fir or spruce and either glue up or build solid.

[pcford]

By the way...laminated stock is a pain in the butt...different grain directions make working with hand tools difficult.

Also, contrary to the opinion of a personage that some people here regarded as a wood expert, air-dried and kiln dried fir are totally different woods. Air dried works much better.

[David G]

rob,

You're right regarding the strength of the pseudoacacia. I was going mostly by memory, and should have looked up the tables. A quick look at the FPL data yields the following - all at 12% m.c.

SPECIES ----- Specific gravity----- Mod. Rupture----- Mod. Elasticity

Sitka spruce ----- 0.36 ------------ 65k --------------- 9.9k
Doug fir ---------- 0.48 ------------ 85k --------------- 13.4k
White ash -------- 0.60 ------------ 103k -------------- 12k
Black locust ------ 0.69 ------------ 134k -------------- 14.1k

Digging into "World Woods in Color", by Lincoln confirms my other comments.

Thanks for the correction.

Also, I have to agree with Pat's two comments about doug fir. Air dried is different . It works easier, splinters less, and is more stable in a marine environment. I'd much rather work with one solid stick for shaping a sprit or spar of any sort. Not that the laminated would be weaker, but because of the pia factor of grains going various direction, and (to a lesser degree) concern over the long term about the glue joints.

[marcin]

If laminated, what would be the glue of choice?

'poxy frozen snot, resorcinol, other?

[David G]

If laminated, what would be the glue of choice?

'poxy frozen snot, resorcinol, other?

Generally speaking, I'd think first of resorcinol, then epoxy.

One could also consider Titebond III, but I see two potential problems. First, it doesn't have the track record of the other two (though I suspect it'll turn out to be reliable and long-lived). Second, all PVA's are subject to creep under stress. That's the reason I seldom use them for a bent lamination, and it's a trait that might factor into your thinking.

[Thorne]

Really interesting article in this month's WB Magazine -- explains why the lignin in softwoods is different than hardwoods (softwoods are more primitive), when air-dried is nearly as strong as wet wood, and much much more.

That said, a bowsprit is a spar like other spars -- so bottom line is that you'll probably want to stick to woods commonly used in spars.

[kc8pql]

I laminated mine. Three layers of V.G. Sitka spruce, glued with resorcinol to make a 7"X7"X12' blank. Finished weight is about 75 lbs. D.Fir was my first choice but I already had the Sitka on hand, leftover from building the mast. It's worked out just fine.

[David G]

I laminated mine. Three layers of V.G. Sitka spruce, glued with resorcinol to make a 7"X7"X12' blank. Finished weight is about 75 lbs. D.Fir was my first choice but I already had the Sitka on hand, leftover from building the mast. It's worked out just fine.

I'd be much happier working with such a glueup in sitka than in doug. fir. Since the fir is so available around here, I've worked with a lot of it in my life. Those who've spent some time with it know that it likes to split - to seperate along the interface between early wood and late wood. And, once a split starts, it wants to keep going. I'm comfortable reading the grain on a stick of fir, and working it in a manner to minimize the tendency to split. If you put three sticks together, however, I'm outnumbered. The grain directions are much harder to decipher. pia!

Sitka doesn't share this quirk to any large degree.

[Jay Greer]

Interesting to see here that this boat is one that I did the master molds for many years ago. The leaves were very fiddly to make so that they would pull clean from the mold.
So far as making a new sprit is concerned, I usually use spruce for sprits under five or six feet. Next choice would be fir. Locust is overkill as it is over strong and not all that light. A sprit that will sheer off in a collision is better than one that is overly strong as it will absorb shock that could end up producing structural damage to the hull; even a glass hull. Normally I like to use a one piece quarter sawn blank. If glued, I would use resuorcinol or Weldwood glue.
Jay

[Epoxybreath]

Thanks all for the replies. The owner likes to get out sailing on those days blowing a solid 20+. Reefs when needed, but not afraid to carry some sail and plans on some limited but nonetheless Offshore excursions. The owner and I were looking at locust based on the knowledge that at least 6 of these have been replaced with teak and sort of playing follow the leader. I looked for something with similar properties and came across the Locust as perhaps a good fit without the wallet emptying aspect (and I have a stock of nice stuff coming along on the racks.) The cranse iron is bronze so no issue there and didn't think that the 15-20 pound difference in weight was a big deal.
We had not considered the aspect of it needing to shear off in a collision. The boat is not raced, but there are plenty of less than careful boaters on the Chesapeake and accidents do happen so this will certainly have to be pondered.

[JimConlin]

...The cranse iron is bronze so no issue there and didn't think that the 15-20 pound difference in weight was a big deal....

The bow is the second worst place to gratuitously add 20 lbs.

[floatingkiwi]

The bow is the second worst place to gratuitously add 20 lbs.

And the first? The top of the mast, perhaps?

[David G]

And the first? The top of the mast, perhaps?

The waistline... just ask Memphis Mike

Sorry... yes, I'd say up top.

[WannaB]

We are currently in the process of building a bowsprit for our Friendship sloop. The original was 3 laminated boards.

My understanding was a previous owner found it too costly each month. So, a modest trimming of 4 1/2 feet spared them pain.
I saw this as a major problem, it's a Friendship sloop for goodness sake!!!

I opted for sitka spruce as was the original but a one piece this time. It is 4"x14' from bit to tip finished. This is not an insignificant amount of weight even in spruce hanging out front.

Best of luck to you with whatever you decide to do with yours.

Keep them sailing.

Ralph