Ken...see my answers below.... Bob Eeg
From: wesi@comcast.net To: montgomery_boats@mailman.xmission.com Date: Thu, 9 Jul 2009 18:59:37 -0700 Subject: M_Boats: Repairs to M-15
To the Group;
I recently bought M15 # 128 which I knew had some damage at the keel/hull connection over the rear keel roller which turns out to be under the aft bulkhead plywood panel. Jerry if you are out there this is the boat we discussed last month that you said you would like to look at. I would be glad to bring to you as soon as I get the hubs I ordered and am mobile. Anyway the gel coat cracking looked pretty minor so I thought I would open it up to see if there was any structural damage to the fiberglass fabric. What I found is that the fiberglass thickness at the hull/keel joint is very thin. It looks like only two glass layers and probably isn't a full 1/8" thick. Needless to say when I removed the damaged fabric I went clear thorough on one side. I first thought that I need to back it up from inside but it is a very hard area to access. Then I thought I could remove the cockpit floor or maybe install a watertight access port in the cockpit floor. But as I gave it more thought I decided that I am concerned about the thin layer of glass in an area that needs strength. I am now thinking of adding a four layer or so fillet along the outside of the keel/hull joint all the way around ( maybe flaring to 10" or so wide on the last cloth layer). I thought I would use epoxy and structural fabric. I think four layers should be enough and then I would finish and flair with Marine Tex for the UV protection and extra strength. I'm not too concerned with aesthetics as the boat is old and has a bunch of dings anyway. I realize this will change the underwater profile a little but it doesn't seem too critical.
Has anyone tried such a repair?
I WOULD GRIND OFF THE GELCOAT ON THE OUTSIDE; LAY UP A LAYER OF MAT AND ROVING; USING WEST SYSTEM EXPOXY; SAND, FAIR AND GO AHEAD AND USE MARINE TEX PAINT. OVERLAP 8 INCHES ON THE HULL TO THE KEEL BULB AND THAT WOULD BE PLENTY STRONG.
Is everyone's keel/hull joint this thin?
NO. USUALLY A LITTLE THICKER. OBVIOUSLY IT WAS STRONG ENOUGH OR THE BOAT WOULD BE FLAT BOTTOMED BY NOW. FIBERGLASS IS MUCH STRONGER THAN WE REALIZE.
Does my approach seems reasonable?
YES
Is four layers of fabric enough?
ALL YOU NEED IS A CLEAN, GELCOAT FREE AREA TO LAY UP A REINFORCING REPAIR. PREPARATION IS A KEY FACTOR. AFTER GRINDING (WITH A MASK) ALL THE GELCOAT OFF; CLEAN THE AREA WITH ACETONE; PRECUT ALL THE MATERIAL BEFORE HAND AND WET OUT THE PIECES ON DRY CARDBOARD; WET OUT ONE LAYER OF 2 OUNCE MAT; PRE WET THE HULL AS WELL. DAB ALL THE FLOATATION OUT (BUBBLES)...THEN WET OUT SOME 18 OUNCE WOVEN ROVING (PRE CUT) LAY THAT ON TOP OF THE MAT...DABBING AND USING A RUBBER SQUEEDGEE TO MAKE IT SMOOTH. LET IT KICK OFF. SAND THE BURRS AND BUMPS. FILL ANY HOLES WITH A MIX OF EPOXY AND TALCUM POWDER. SAND AGAIN AND PAINT WITH MARINE TEX. THIS WILL WORK JUST FINE. ONLY 2 LAYERS. BUT ON TOP OF WHAT YOU ALREADY HAVE. NO WORRIES. AS YOU GO AFT, YOU COULD OVERLAP ONLY 4 INCHES AND THAT WOULD DO JUST FINE.
Jerry if you are out there is this a good idea or should I get access to the interior?
GETTING INTO THE INTERIOR IS NEAR IMPOSSIBLE FOR THE KEEL AREA. THE LINER IS UP AGAINST THE HULL KEN.
If this isn't an appropriate subject for the group I can be reached at email wesi@comcast.net.
As always I appreciate the help I get from other members of this group and am especially glad that we have Jerry and Bob as lurkers. Who would think that you could still get advice from the builder(s) on a 30 year old boat.
I HAVE A NOSE PIECE FOR YOU. BTW.
Thanks, Ken Wheeler M15 # 128. _______________________________________________ http://mailman.xmission.com/cgi-bin/mailman/listinfo/montgomery_boats
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