In case you aren’t on our mailing list, we put out a ‘Keel Bolt Maintenance Bulletin” this week.

Everyone should read this.

It is on the Waterline Systems website. The direct URL is:

http://www.waterlinesystems.com/DIY/default.php

While you are at the site, you should sign up for our mailing list. There is a link in the news section

Will

Please HELP – I bought my first sailboat ever – a 1979 J24. Sellers are a family of sailors. Boat was not in the water. But after looking it over for 2 hours and listening to what was done to it – I made an intuitive decision and bought it along with trailer – and brought it down to Atlanta. Had it rigged on dropped in the lake on Thursday. 36 hours later I noticed water in the sump area around the keel bolts were the lift hook is. Rain? Sailed Saturday and then again on Sunday (hard) with water washed over the toe rails! Then I saw water in the sump and in the sump just forward of that. I drained and dried them both. Monday night I checked again – and yep water in the sump to the stern where the lifting hook is. The water level (so far) has stopped at the top of the keel bolts. How serious of a problem have I bought? Can it be repaired by simply torquing down the keel bolts? What other options do I have? Should I haul it out and have the keel and area around the hull checked? Can I go a season? What type of cost am I looking at? A lot of questions but all advise will be greatly appreciated. Lew at rifs@mindspring.com

@will: Thanks for the alert. You referred to Waterline’s new keel bolt torque spec, which is 48.7 ft-lbs for the 5/8 bolts on my 1981 J24.

This is way lower than 100 – 120 ft-lbs recommended by TPI in this old verm-job article (http://www.j24class.org/usa/faqs/verm_repair.htm). That old spec is in line with general recommendations for bolt torque, for example: http://www.engineersedge.com/torque_table_sae.htm, which is 96.7 ft-lbs for 5/8 316 SS bolts. I assume most older boats came out of the factory with bolts torqued to 100 ft-lbs.

So:

Has bolt science improved?

The cited ISO standard 12215-9.2 is apparently a work-in-progress?

Why is the new torque spec so much lower than the old?

What is the risk to boats with now “over-torqued” keel bolts, who are unaware of this maintenance bulletin, and already splashed for the season?

The ~100ftlb is designed to not overstress bolts to attach metal to metal. The bolt is the weak link. When bolting to fiberglass, the fiberglass is the weak link and you don’t want to damage it. You want enough torque to hold the keel firm but don’t want to concentrate stresses at the bolt holes any more than necessary. Somebody did the analysis (probably after the J80 keel loss incidents) to get the ~50.

I’ve been getting a lot of e-mails on this topic. Here is a recent reply:

I’m not an engineer by any stretch. When we were preparing that article, Al J did the research on the table, and used the ISO stuff. Looking at your links, I can see that there is a wide range of numbers. Dry vs Lubed and various grades of steel all seem to make a huge difference. We recommend a good cleaning and then application of an anti-seizing compound. I don’t know the lubricity of Anti-seize vs Oil specifically, but my wrist tells me it is much more lubed than dry.

Again, I’m not an engineer, but on my boat we are using Al’s numbers. My feeling is that once you have good clamping force, geometry and the adhesive force of the 5200 is going to keep the keel attached. ( Ever try taking one off? They are glued on there pretty freaking good.)

I think I’m less concerned with the keel coming unscrewed and falling off, than I am about overstressing the tops of the bolts and dropping my boat on a buddy’s head.

From what I’ve read and through personal experience, I know that it is no real trick to rip the head of a bolt clean off with a big wrench. That added to the threat of crevice corrosion scares me more.

In short, I don’t think I have the perfect, every boat, every situation answer. I do feel that over torqueing , particularly on the aft nuts with the lifting gear has the potential to kill someone. I have a torque table from the International Standards Organization, provided by my yacht designer. I don’t think that this 100% guarantees that I won’t break a bolt, but if I do. At least I’ll feel like I covered my bets as best I could.

As I try to stress over and over, if you have a concern with your boat, consult a qualified marine surveyor. He will have, or have access to specific knowledge to give you good advice on your specific situation.

Yours truly,

Will Harris

Waterline Systems