Back to the dreaded bowsprit material construction considerations

[Eastward ho 24]

Hey big girls wanna go sailing? Ha ha BBQ in the bow in a blow?

[Eastward ho 24]

I like the phrase Ludacris about the 1/4 SS. Really think 1/4" is ludacris? I wouldn't know enough to say it is or it isnt. But I would like to be prepared for the worst and not worry about gear failure.maybe ive been into my "storm tatics" and " heavy weather sailing" too much. Guess your right though I've only got a high cut Yankee out there as is, And it's compression loaded. I Guess the worst side loading will be at anchor in waves with a snatch block to the sprit end Or if I were to get it up over a dock accidentally. But hell the 4x4x1/4" 6061 alu is only 250$ for an 8 foot piece. And there's a good alu shop up the street I think I'll start with alu and have the ss on backup. Gonna weld the lugs on the ends. The SS clevis pins 1/2" should not go directly into the lugs? How do I go about attaching the turn buckles? And I guess them pretty bronze rollers are out. I haven't seen much alu to brnz but that's apparently alot worse then the SS to alu.

[Benz]

For your boat, 1/4" SS would be ludicrous. I have a heavy (ten-ton) 31' pilot cutter, and went through the same mental processes you're going through right now when under construction. Then I sailed it 12,000 miles, and realized that in my enthusiasm I made everything stupid big. Better than too small, but there's a balance to be found.

If you are concerned about SS or bronze pins on aluminum, you can overdrill the holes in the tangs and slide in a G-10 bushing. I have some G-10 between my aluminum deadeyes and their bronze pins which makes them play nice, and again, Tef-gel is your friend.

I wouldn't bother running the anchor tackle through a snatch block on the bowsprit. Better to keep it off the bobstay by designing a fitting on the bobstay chainplate through which your snubber can lead--that keeps your rode angle better, and puts the strain where you're best designed to take it.

There's no need for bronze rollers--get delrin ones that will slide onto a crosswise pin in the bowsprit, with a nut or big clevis pin on the end of the pin to keep the roller from falling off. Keep it simple. You never hang the boat from there anyway--that's just for deployment and retrieval. The boat should be on a snubber.

[Eastward ho 24]

That's just what I needed to hear thanks allot!

[Eastward ho 24]

Sprits coming along....where the old one was it had (2) 3/8 allthread rods through bolted to the deck. Wahat I want to do; drill a hole through the sprit insert a pipe and socket weld both ends and grind it flush. Thus making the sprit air tight. I'm having a really hard time trying to figure out what size pipe would be a perfect fit for a piece if 5/8 all thread..I mean obviously I'd need an I.d. of slightly larger then 5/8. this is hard to figure out. Does any one know this info off hand or how I'd find it? Or should I just add a weep hole in the sprit and let it open to the atmosphere? Also In the past I've made the mistake of using SS bolts in my alternator and they break off eventually since the work harden and break. Should I be using SS All thread for this application?

[sailah]

Go to McMaster. They have a handy menu on left to sort through using ID, OD etc.

Closest I can find for bigger than 0.625 is 0.652" which is a somewhat sloppy fit.

https://www.mcmaster.com/9898t24

https://www.mcmaster.com/standard-al...-hollow-tubing

Your other options are to have a machine shop run a reamer through some 0.620 and that 0.005" would be a snap. Often all thread is undersized anyways and is likely to not be a true 0.625" so the 0.620 tubing might work perfectly. You'd need some calipers to check.

[Benz]

A 5/8" bolt, or allthread, is designed to fit though a 5/8" hole. If it doesn't, a quick ream-out with a 5/8" drill will do the trick--it's pretty easy to remove a smear of material, even if it's stainless.
If the bolts or allthread are tight, you don't need to worry about work hardening--an alternator vibrates a whole lot more than a bowsprit.

[Eastward ho 24]

I get most of my metals from online metals. Not sure if I want to go 1/2" or 5/8 , but in their seamless 316l tubing I found; .5, .51, .527,.532,.555 id tubing and similar tolerances in the 5/8" they all seem pretty tight do you agre? The .5 has a wall thickness of1/4" the rest are really thin tubing. Am I looking for some strength to prevent crushing or do you think I should use the really thin stuff just to make it air tight?

[Argyle38]

Would be interested in seeing some pics of the project when it's done.

I've heard of replacing the bowsprit with metal, but have never seen a finished project.

[Eastward ho 24]

I'm gonna document the build for the forum in case anyone wants to dupe it, they wont need to ask all the same questions...my only concern is the weight . The spirit I have now isn't original and its rotted but I'm about double the weight might be an expensive lesson learned.

[Benz]

Originally Posted by Eastward ho 24

I get most of my metals from online metals. Not sure if I want to go 1/2" or 5/8 , but in their seamless 316l tubing I found; .5, .51, .527,.532,.555 id tubing and similar tolerances in the 5/8" they all seem pretty tight do you agre? The .5 has a wall thickness of1/4" the rest are really thin tubing. Am I looking for some strength to prevent crushing or do you think I should use the really thin stuff just to make it air tight?

Thin stuff--how easy do you think it'll be to crush square tube? But a greater consideration is that welding thin stuff to thicker stuff is harder than welding stuff with the same thickness.

My opinion here, however, shouldn't matter much--after all, I wouldn't use stainless at all, and my experience with it is very limited. I only know that I hate working it, hate keeping it shiny, hate worrying about crevice corrosion.