Wood, aluminum, or steel for new bowsprit.

[Deltasailor]

Originally Posted by F51

Yet again time to play catch-up on the sprit. The original bowsprit was milled from one 9"x9" x 13-foot piece of mahogany. I'm tired of trying to keep the rot at bay, so I am looking to replace the whole thing with teak, aluminum or steel. Even here in teak country a 13-ft chunk of a tree is not going to be cheap. First quote for the teak was $3100. Ouch! Now I know why the builder used mahogany! I can get aluminum or steel square tube for a lot less. I am leaning toward the steel since any competent welding shop can cut and reseal the front part so it looks like a sprit. Then weld on some pad eyes to accept the stays.

Do I seal it up airtight or take it to Guatemala city to be galvanized inside and out? I'm sure I could find some good hard paint to adhere to the galvanizing.

Who on the forum has had experience building a bowsprit out of metal? Any special problems or concerns?

Thanks for any help. The combined wisdom here is awesome!

I built a bowsprit out of 2" stainless tube for my endurance 37' Designed by Peter Ibold. No problems I'm sure the design is available.

[Dave22q]

Strange dimension, 13'. Does it need to be so long to reach a cross brace? Steel or aluminum easiest, AL no corrosion issue. Why rectangular tube? a slightly thicker channel might be easier. No welding, just use bond breaker for bolted fittings.

[Terra Nova]

Originally Posted by Dave22q

...Why rectangular tube? a slightly thicker channel might be easier...

Channel is no good for a bowsprit.

[model 10]

Originally Posted by Terra Nova

Channel is no good for a bowsprit.

If the load is right down the sprit, (compression load), round is the the strongest, lightest.

[maxingout]

Steel or wood works for me.

I am not comfortable with any welding on aluminum if it is going to come under significant and repetitive loading.

[hafa]

+1 for stainless tubing. Best overall strength and durability.

[UNCIVILIZED]

I understand the aversion to welding aluminum, at least in theory. But there are an awful lot of welded components on spars out there, most of which give no problems. Goosenecks, Shroud & Stay Tangs, Mastheads/Masthead boxes, Sheave boxes, Spreader Brackets, Hulls, & Keels, along with Rudders...

And if one wants to get technical about things, it's not great practice to structurally load welds in steel. But it's done all the time, & in many of the same applications as aluminum listed above, & more.

With things done right in terms of engineering & welding practice, there shouldn't be much in the way of issues, if any. And making things "modular" so that you needn't take off the whole sprit to have it modified or repaired. It's not as if it's rocket science, nor anything new.

[thudbranch]

If you are going to use galvanized steel tube, then you should know that the tube can not be completely closed while galvanizing. It needs a vent hole or two while galvanizing. You can then close the hole(s) with threaded fasteners or bolted on cover after galvanizing.

[Dave22q]

Originally Posted by Terra Nova

Channel is no good for a bowsprit.

Very clear statement. Sadly it is ignorant. The primary force on a bow sprite is resistance to bending up or down. Rectangular tube is stronger than channel of same thickness but not by a whole lot. More importantly, channel lets you avoid welds as connections can be easily through bolted. Flat bar could also work but is at a major strength disadvantage to channel or tube. Depending on the deck layout a 3/8" or 1/2" bar might be better than a much thicker cross section although he had been living with 9".

[Terra Nova]

22--you seem to know a lot that simply isn't so.

If what you said were true (it isn't) you'd see spars made of channel and flat bar. This has nothing to do with deck layout. It has everything to do with using an efficient shape for compression loading.

[Mike Banks]

Have you considered using fibreglass? It works fine for fishing rods--and it is strong and light.

I would be using glass and epoxy over a PVC core. Being hollow and corrosion free--wiring and screws etc should not cause problems, For the end I would use a Cranse iron cap of 316 or better stainless for the welded eye fixtures for bow stay and lower and lateral braces

[zeehag]

why only consider teak?? there is also ipe and other hard woods that love sea water. use one of those. ipe is gorgeous and resists rot and insects.
my sprit will be constructed of huanacaxtle / ipe/perote wood from mexico, wherein i am cruising currently, at a pricing of less than 3 usd per foot. my 14.5 ft mizzenboom was 1200 pesos at 16 pesos to one usdollar. not bad shopping i think.
this is a beautiful and strong and resistent to all issues kind of wood.
get creative with your resources. they are out there.
donot forget that sprit is a very active part of your kinetic rigging and sail trims. also anchoring and other sprit involved usage. use strong hard materials designed for the purpose intended. good luck.

[Panope]

Unpainted, aluminum pipe spars have the following qualities:

-Reasonable INITIAL cost.
-Lowest maintenance (none) of any conventional spar material. Therefore, lowest LONG-TERM cost.
-Very strong, tough.
-Quite light.
-Easily modified.

-May not match the aesthetics of an otherwise "wood accented" yacht.

A bit of taper can be built into the spar end by removing "slices" and re-welding.

[Benz]

Panope: what a gorgeous masthead! That is some nice looking design and work.
Thanks for those pictures.

[Panope]

Thanks, Benz.