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-   -   A wet bilge is MORE than just a nuisance ! (http://www.sailnet.com/forums/gear-maintenance/43505-wet-bilge-more-than-just-nuisance.html)

Maine Sail 05-25-2008 07:57 AM

A wet bilge is MORE than just a nuisance !
 
The owner of this boat asked the yard to torque his keel bolts only there was NOTHING left to torque. Boat is mid 80's..!

These were originally 11/16 stainless bolts that has suffered from crevice corrosion and lost more than 30% of their diameter.

I often hear folks say a wet bilge is nothing more than odor and interior cabin moisture well, it is not and can mean much worse.

This is an expensive repair.. Do your best to keep your bilge dry, if possible, especially if you have an external lead keel..

IF YOUR KEEL BOLTS ARE LEAKING DO NOT JUST TORQUE THEM DROP THE KEEL AND FIX IT BEFORE YOU NEED ALL NEW BOLTS!

As our boats get older and older we WILL see more of this..!!

http://www.pbase.com/mainecruising/image/97591698.jpg
http://www.pbase.com/mainecruising/i...2406/large.jpg

trantor12020 05-25-2008 08:57 AM

FRIGTHENING !! The thin part between the threads, is it due to metal loss or intended design ?

Maine Sail 05-25-2008 09:10 AM

No !
 
Quote:

Originally Posted by trantor12020 (Post 319800)
FRIGTHENING !! The thin part between the threads, is it due to metal loss or intended design ?

The thin part is likely from crevice corrosion and is not intended.

Crevice corrosion occurs with stainless steel when water and a lack of oxygen are present. If the keel bolts leak they can rot out from crevice corrosion, in the keel stub, where you can't see them eroding. No oxygen and leaking bolts can cause this phenomenon.

Also, if an owner attempts to seal a leak by covering the bolts with an epoxy or sealant, with the good intent of saving them and stopping the leak, and they continue to leak, crevice corrosion can eat away the keel bolts, under the "protective coating", and out of site, until they disappear and whither away.

Keel bolts can leak from BOTH sides. Keeping a dry bilge will alert you to a leaking keel bolt, from the outside, and prevent crevice corrosion from the top side at least. The worst ting you can do to a known leaking keel bolt is to seal it off from the inside or torque it until it stops leaking into the boat. If it's leaking in from between the hull to keel joint you have only sealed in the water, that already leaked in, and have just exacerbated and made the potential for crevice corrosion worse..

BenthosCritter 05-25-2008 11:58 AM

Good reason for getting a catamaran. :)

Stillraining 05-25-2008 12:19 PM

Main:

About a month or so ago you posted pictures of your keel bolts with the comment " Not bad looking for a thirty year old boat" (Paraphrased) I almost replied " Ya but that dosent mean much, its what you cant see that you have to worry about" but I knew you knew that so I didnt say anything...

Mine also look brand new like yours ...but I wonder???

Someday I may peal my hull...If I do.. Im dropping the keel to find out.

Now the $1.98 question...How the heck does one install new bolts?

TxLnghrn 05-25-2008 12:30 PM

New Keel Bolts
 
I have a recommendation from a well respected surveyor on for a similar, but less serious (hopefully) ;) issue on the 1987 Pearson 31-2 I just purchased. According to him the fix is to not replace the bolts, but to drill in new lag bolts to reinforce. Then of course acheive and maintain a dry bilge and seal all the bolts.
Michael

Maine Sail 05-25-2008 01:22 PM

Quote:

Originally Posted by Stillraining (Post 319836)
Main:

About a month or so ago you posted pictures of your keel bolts with the comment " Not bad looking for a thirty year old boat" (Paraphrased) I almost replied " Ya but that dosent mean much, its what you cant see that you have to worry about" but I knew you knew that so I didnt say anything...

Mine also look brand new like yours ...but I wonder???

Someday I may peal my hull...If I do.. Im dropping the keel to find out.

Now the $1.98 question...How the heck does one install new bolts?

But, I've removed the nuts, checked the threads and I know the keel to hull joint is bone dry and my keel bolts don't leak. My boat has been in the water for a couple of weeks and my bilge still has dust in it...:)

Keel Bolt Replacement:

The best, strongest and safest method of keel bolt replacement is done by Mars Metals and a few others. This is the description from Mars:

"The bolt replacement process goes through these general steps:

• The damaged bolts are identified when the keel arrives.
• The bolts are removed through one side of the keel. This is done with a great deal of skill with a torch taking
the upper surface of the lead away.
• The old bolt is used as a pattern for the production of the new bolt. Most keel bolts are J hooked or bent in
some manner.
• Once the old bolt is removed there is a “saddle” of lead remaining, creating the position for the new bolt to
be held.
• The new bolt is fabricated from new matching material.
• The new bolt can even be welded back into the bolt cage right in the keel.
• The new bolt is fused into place. Lead is melted back on top of the new bolt, fusing the original lead and
the new lead, making the repair as strong as the original keel.
• The entire surface of the keel is faired, both sides.
• The root cord is cleaned.
• The remaining original keel bolts are cleaned and readied for installation on the boat."


Here is a more detailed description:
Keel Bolt Replacement


Anything other than completely installing new J-bolts is a band-aid at best. I should know I used a band-aid approach on one of my old boats and would never, ever consider doing it again!! This was before I, or my boat yard, knew of the Mars Metal process for replacing keel bolts..

TxLnghrn 05-25-2008 02:05 PM

Thanks for the response Halekai. The surveyor did mention the Mars method as well as another method that involved cutting a window through the keel, running a rod and tying new bolts to it. But he felt that with the limited corrosion on my bolts (three out of ten showing any damage). that the lag bolts providing some extra support would be more than sufficient, for my style of cruising.

Rockter 05-25-2008 07:03 PM

Stainless typically is an awful material when it gets starved of oxygen and chlorides (from seawater) are present.
Give me an encapsulated keel every time, made from lead, encapsulated in GRP.
That way there are no keel bolts.

xort 05-25-2008 08:20 PM

Are you talking about deck stepped masts? It would seem impossible to keep the bilge dry with a keel stepped mast. Too many holes in the mast that will let rain water in. Maybe not a lot but some will get in.

I also have 2 aircons that dump condensate into the bilge. Any easy ways to keep that out?


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