Compac 16' Keel advice needed - Page 2 - SailNet Community
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post #11 of 20 Old 11-16-2019 Thread Starter
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Re: Compac 16' Keel advice needed

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Interesting job. Are you going to remove the bilge to access the ballast or go through the encapsulation from the outside. The bilge would leave an intact encapsulation to refill, but then you need to structurally replace the bilge. The encapsulation probably needs to be reinforced, but more curious is how you insure a good bond to the encapsulation, when you refill.

The lead will change the weight of the ballast, but I doubt that will make sailing her all that different. If significant, it may alter her waterline though. Is your plan to imbed the ingot into an epoxy slurry of some kind? Insuring this slurry bonds to the existing glass?
yes I will use some type of epoxy slurry. I am going to pop the cap to get access to the encap.

Last edited by Chuck1947b; 11-16-2019 at 05:01 PM. Reason: needed to add some info
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Re: Compac 16' Keel advice needed

The ingots may or mayn't fit together well. I made up a mould of 2" angle irons welded with flat bar strip for ends. they fit together well one row up to next row down. Length could be how wide the cavityy is. after lots of strengthening glass. Fill with slow kicking resin. Same weight as concrete but lower down is good.
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Re: Compac 16' Keel advice needed

Seems to be a lot of work that may be unnessary Maybe a bit of tear off in the bilge and decide if a good layer of glass will do while the water. drips out below.
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Smile Re: Compac 16' Keel advice needed

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Seems to be a lot of work that may be unnessary Maybe a bit of tear off in the bilge and decide if a good layer of glass will do while the water. drips out below.

Well, I've decided on the lead. According to the reaearch I have done you get a lot more bang for the buck if you use lead. Also I want to make sure it good and dry so the top is getting popped and the concrete taken out. I want a total restoration and not be worrying about a keel being half repaired, or anything else for that matter.
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Re: Compac 16' Keel advice needed

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The ingots may or mayn't fit together well. I made up a mould of 2" angle irons welded with flat bar strip for ends. they fit together well one row up to next row down. Length could be how wide the cavityy is. after lots of strengthening glass. Fill with slow kicking resin. Same weight as concrete but lower down is good.
I've seen on other sites and the net where people have good luck cutting lead with a course, carbide tipped skil saw, miter saw, table saw, etc. So I can always cut an ingot into filler pieces and then slurry it in.... I hope...lol. You know concrete ballast just sounds like a bad idea, esp since the top of the ballast is the lowest point in the hull making it an ideal little reservoir for any intruding water. I thank god I'm in florida and don't have any freezes to worry about or good bye keel I would think. This may sound dumb but why the "strengthening glass"? If you lay and fill around the ingots and then slurry it, that should suffice, no?
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Re: Compac 16' Keel advice needed

One advantage of concrete is absolute symmetry in weight distribution. When you place the ingots, you're going to need to distribute them very evenly and intently.


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Re: Compac 16' Keel advice needed

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One advantage of concrete is absolute symmetry in weight distribution. When you place the ingots, you're going to need to distribute them very evenly and intently.
Good piece of advice, I'll try to send in pics as I go along. I appreciate all your concern and good points/advice.
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Re: Compac 16' Keel advice needed

Talk to ComPac (Hutchins Boat Works). They replaced my stainless steel center board trunk with a new fiberglass one for around $1400. I have a 2002 SunCat. Great people to work with.



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post #19 of 20 Old 12-04-2019
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Re: Compac 16' Keel advice needed

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Originally Posted by Chuck1947b View Post
I've seen on other sites and the net where people have good luck cutting lead with a course, carbide tipped skil saw, miter saw, table saw, etc. So I can always cut an ingot into filler pieces and then slurry it in.... I hope...lol. You know concrete ballast just sounds like a bad idea, esp since the top of the ballast is the lowest point in the hull making it an ideal little reservoir for any intruding water. I thank god I'm in florida and don't have any freezes to worry about or good bye keel I would think. This may sound dumb but why the "strengthening glass"? If you lay and fill around the ingots and then slurry it, that should suffice, no?
No, Laying and filling around the ingots and then slurrying over it is not a complete solution. (By slurry I assume that you are suggesting using a slightly thickened polyester resin since anything thicker than cough syrup won't flow into voids and anything thinner will crack simply from the heat of the thermosetting process and will shrink away from the encapsulation membrane failing to make a bond.)

By way of an explanation of why a minimally structural membrane is needed above the ballast, the bonding of the ballast keel to the encapsulation envelope is a key structural component in the strength of the keel and hull above. The ballast serves as the 'web' of an 'I' Beam allowing the fiberglass on either side to act and flanges. When the bond is intact, this is a very stiff structure that concentrates a lot of the stresses into a very small area where the keel turns down into the encapsulation envelope both fore and aft and side to side. Over time these stress risers take a toll on the strength of the laminate in those area weakening these critical areas in the boat. Adding to that is that boats like the Compac are often trailered with with the keel resting on the trailer and supporting the weight of the boat. The bumps in the road will result in numerous repetative small impacts to the critical laminate in the area where the keel turns down into the encapsulation envelope, further taking a toll on the strength of the laminate in this area.

While popular mythology suggests that the majority of cases where keels are lost are the result of keel bolt failure, in reality, an extremely large number of cases occur due to a failure of the laminate both fore and aft and side to side of the actual keel connections. In that regard, the current fledgling studies of keel losses show that its not just bolt on keels that are being lost.

Beyond that, in a hard grounding, the ballast keel is pushed upward against the weakened laminate and the bond between the ballast keel and encapsulation envelope is stressed and breached by the deflection of the skins of the encapsulation envelope. If the encapsulation envelop is pierced by the grounding, the boat is likely to minimally potentially be un-repairable and more extremely sink. A structural membrane, ideally coupled with transverse framing, reduces the stresses on the ballast to hull bond and on the laminate at the turn-down into the encapsulation envelope providing a much higher probability of surviving a hard grounding with a repairable boat.

If you are going through such an extreme effort to improve an otherwise intact and adequately constructed boat, then it would seem that installing a structural membrane above the ballast would be a pretty cheap bit of insurance that no matter how long you own the boat, almost no matter how you abuse the boat, and no matter where you trailer it, the repair will remain solid.

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post #20 of 20 Old 12-06-2019
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I owned a late 70s Com Pac 16 and when I got it it had suffered a grounding at the leading edge of the keel and the glass encasement at the bottom had split from the forward edge down the port side at the turn about 2/3rds of the way aft. The ballast was solid lead and was exposed, obviously. I repaired it by first cutting back and dressing up the ragged edges of the keel encasement, then used a tube of West Marine self-mixing Six10, the caulking tube stuff, which I injected between the lead keel and the fiberglass encasement, all along the bottom. I then used a floor jack with a 2x4 on it so it applied pressure the full length of the bottom of the keel and sandwiched the encasement up against the lead keel. Six10 was forced out as it the space between the keel and encasement was closed up. I spread the excess that squirted out along the gap to fill in the edge that I'd cut back and dressed up. Once the epoxy had cured I sanded the edge smooth and roughed up the encasement up several inches along the leading edge, bottom, and port side of the keel, before applying fiberglass woven roving wetted out with epoxy. Once cured I fared the keel repair using an orbital sander. Then I used plain old white spray paint to finish it up. Looked pretty good and never had any further problems with any delamination or any other issues. The boat had been on the hard for a while before doing this and so the keel was fully dry before I effected the repair.
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