Axle bolt size for anchor roller?

[sharkdiver84]

The setup that came with my boat is a 3/8 threaded rod going through the sprit, roller, and or edge of the platform. I'd like to change to 1/2 but it requires major redesign and additional holes in the sprit. Could I get away with leaving the 3/8? What is a typical size?

[Spot]

Hey Shark,
Length of boat, weight of anchor, type of rode, picture of current situation...might help get you quicker and better answers.

(PS sorry, just saw the boat over here: https://www.cruisersforum.com/forums...ml#post3795359 )

You could try ordering a bolt that is 1+1/2" (40mm) longer or whatever it take to make sure that the smooth portion of a partially threaded shaft is hitting the bearing surfaces.

[sharkdiver84]

Yeah thanks. I think it would be better for the part that touches the roller, but it's so long I've only been able to source rod threaded rod so far. It's probably possible to put pipe over the threaded parts to prevent the roller from getting chewed up, but you're right, bolts would be better. It's a big boat, 38 ft heavy displacement, and I'm gonna try to carry 2 45 lb anchors. That's where I think the 3/8 bolts might be inadequate. Probably not for when all the scope is out, but trying to break an anchor free with that worries me. An I being paranoid?

[Spot]

My boat carries a 256 # swing keel on a single 1/2" bolt but it is not all-thread.
There is no slop and the bolt bears on flat surfaces.
You could fit a solid rod, mark it, and have one end threaded and the other threaded and then welded with a nut.

PS my anchor and boat is much lighter so I would not be the best one to answer. Sounds like the other thread is getting some good comments too.

[wyb2]

What is the span? I suspect you are underestimating 3/8” stainless, but with a long span and a rubber roller not providing bending support, I’m sure it would be possible to bend it. Putting a pipe or sleeve over it of significant wall thickness would add bending support.

In double shear, 3/8 stainless threaded rod could probably rip the bowsprit clean off your boat.

[Jim Cate]

FWIW:

46 ft 12 tonnes, all chain: 5/8" diam bolt, nylon sheave. Has worked for us for 33 years of boat life and lots of full time cruising miles and thousands of nights at anchor. No bending, no perceptible wear on bolt or sheave.

Overkill? Perhaps, but no worries and no damage... and bolts like this are relatively cheap.

Jim

[Pete7]

Originally Posted by sharkdiver84

It's probably possible to put pipe over the threaded parts to prevent the roller from getting chewed up, but you're right, bolts would be better. It's a big boat, 38 ft heavy displacement, and I'm gonna try to carry 2 45 lb anchors. That's where I think the 3/8 bolts might be inadequate. Probably not for when all the scope is out, but trying to break an anchor free with that worries me. An I being paranoid?

Having two threads cut on a 1/2" bar of stainless shouldn't cost too much. If you try to DIY it will need to be a good quality die to cut the threads, with oil and a quarter turn back each full turn or so. A machine shop used to making propeller shafts will use a lathe.

Pete

[NorthCoastJoe]

Why not get a longer bolt and cut off the excess. I just got some 316 bolts from these guys, and had them in two days.

Bolt Depot <orders@boltdepot.com>

[Cheechako]

Originally Posted by sharkdiver84

Yeah thanks. I think it would be better for the part that touches the roller, but it's so long I've only been able to source rod threaded rod so far. It's probably possible to put pipe over the threaded parts to prevent the roller from getting chewed up, but you're right, bolts would be better. It's a big boat, 38 ft heavy displacement, and I'm gonna try to carry 2 45 lb anchors. That's where I think the 3/8 bolts might be inadequate. Probably not for when all the scope is out, but trying to break an anchor free with that worries me. An I being paranoid?

1/2" would definitely be better for that size boat. But at least get bolts in lieu of threaded rod if you can. How long is it?
The other option is to get a SS rod, cut to correct length and have the ends threaded, or just buy a die to thread the ends yourself.
or you can drill a hole through the rod each end, put on washers and cotter pin in the ends, no threads at all.