Carriage Bolts ?!?

Dinghies, day sailers, world cruisers. Many small sailboats make ideal rowboats or low-speed power boats.

Moderator: BruceDow

Mike Worrall
Posts: 73
Joined: Wed Jun 28, 2006 4:18 pm
Location: Los Angeles

Carriage Bolts ?!?

Postby Mike Worrall » Tue Feb 20, 2018 11:57 pm

The image below is from the plans for the 29 foot Francis Drake FG version, specifically the detail for the bulwark cap.

Note that the 1 X 3 cap is secured by an inner and outer 1 X 2 'shear cleat', and that the plans say to attach these cleats with 5/16" 'Carr. Bolts' at 6" intervals? I assume that 'Carr Bolts' means 'Carriage Bolts'.

Really?!?

This seems like a very odd choice; while the 'head' of a carriage bolt would be almost flush with the cleat is was securing, the opposite end - the threaded end - of the bolt would have an exposed washer/lock washer/nut that would be 1) Ugly and 2) Just waiting to snag lines, ankles, toes, etc. As the length of each (P&S) bulwark is over 30 feet, that would amount to 120 exposed bolts / nuts / washers...

Seems to me a much cleaner approach would be to use #12 wood screws at 6" intervals, countersunk to allow for a plug to cover the screw head.

Can anyone suggest why a carriage bolt would be the best way to do this?

MW

Bulwark Cap.jpg
Last edited by Mike Worrall on Sun Feb 25, 2018 12:06 am, edited 1 time in total.

User avatar
hoodman
Posts: 1794
Joined: Thu Nov 10, 2011 8:48 am
Location: Lafayette, IN

Re: Carriage Bolts ?!?

Postby hoodman » Wed Feb 21, 2018 6:04 am

I'm no marine architect but that carriage bolts do seem like overkill for this application. Not to mention that would be horrendously expensive if you used Si Bronze.

User avatar
Stuart
Posts: 580
Joined: Tue Aug 02, 2005 6:43 pm
Location: Canada

Re: Carriage Bolts ?!?

Postby Stuart » Wed Feb 21, 2018 10:31 am

Nothing holds better than a carriage bolt. That's only two bolts per foot...you sure that would be enough.

Stuart

User avatar
NAMEngJS
Posts: 64
Joined: Wed May 27, 2015 10:21 am
Location: Metairie, LA

Re: Carriage Bolts ?!?

Postby NAMEngJS » Thu Feb 22, 2018 7:10 am

You could use a forstner bit and recess the nut end as the sheer rail is 1" thick you should have enough strength left if you recess the nut, this would provide relief from snags.

Dont know if the cap rail is epoxied down as well but for commercial vessels like tug boats, for example, the fenders are usually bolted in place as these are items that are replaced often and it is easier to remove and replace and those are usually bolted at 12" spacing (Though they use larger bolts).
All men dream, but not equally. Those who dream by night in the recesses of their minds, wake to find that it was vanity: but the dreamers by day are dangerous men, for they may act on their dreams with open eyes, to make them possible.

User avatar
steveh41
Posts: 655
Joined: Mon Jun 14, 2010 7:16 pm
Location: Catheys Valley, CA
Contact:

Re: Carriage Bolts ?!?

Postby steveh41 » Thu Feb 22, 2018 9:02 am

I believe the intent is to through-bolt the cleats to the sheer which is by far the most secure way to fasten them. In place of expensive bronze carriage bolts I have used bronze all-thread cut to length with a washer and nut at each end recessed with a Forstner bit just enough to make it flush on both surfaces. The unit is then bedded in thickened epoxy to fill the threads and finished smooth on the outside with epoxy putty. The holes disappear and the cost for threaded rod is a lot less than equivalent bolts.

Steve

PS- Fastening the cleats also appears to reinforce the hull-to-deck joint which would explain the stout construction.
Last edited by steveh41 on Thu Feb 22, 2018 4:29 pm, edited 3 times in total.
The longest journey begins with a single step… then repeat as necessary!

User avatar
hoodman
Posts: 1794
Joined: Thu Nov 10, 2011 8:48 am
Location: Lafayette, IN

Re: Carriage Bolts ?!?

Postby hoodman » Thu Feb 22, 2018 11:07 am

Good call on the threaded rod.


Return to “Sailboats”

Who is online

Users browsing this forum: No registered users and 5 guests