Filling in a deep bilge - SailNet Community
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post #1 of 19 Old 09-23-2009 Thread Starter
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Filling in a deep bilge

I have a Pearson 365 which has an incredibly deep bilge. In fact, when I drop tools into it I literally cannot reach the bottom (I'm 6'3"). Additionally, the extra deep bilge results in having a hollow keel for about 6 inches (forward to aft). A recent grounding resulted in a crack in the hollow section that admitted water into the bilge. Thus, while I had planned on filling it in anyway, the matter is now somewhat more urgent (the boat is on the hard now).

I had planned on filling it in approximately 4-6" with either concrete or epoxy mixed with fiberglass. I prefer epoxy mixed with fiberglass because it would bond to the fiberglass bilge better, but whenever I pour large amounts it cracks and gets extremely hot. So, I have a couple of questions:

1. What is recommended for filling in the bilge?

2. If it is epoxy, is there a method for preventing cracking/excess heat in large batches?

Thanks!
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post #2 of 19 Old 09-23-2009
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IF you fill it HOW would you do glass work inside for current and future repiars ?


The kit they use to fix older J24s cost 750 dollars and its a MUCH smaller area

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If a dirty bottom slows you down what do you think it does to your boat
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post #3 of 19 Old 09-23-2009 Thread Starter
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For the current issue I plan to lay new fiberglass prior to filling it in. By using epoxy reinforced with fiberglass I had hoped to provide enough strength to make it an essentially solid keel, thereby precluding the possibility of any future issues.
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post #4 of 19 Old 09-23-2009
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Foam Core to Take Up Space

Instead of filling in the bilge with buckets of resin/glass, I would get some rigid foam core and shape a tight fitting plug in the deep open area an then either glassing it in with a cap ply OR put down a piece of plastic film, and making a removable glass cap that will allow you access the deep bilge in the future.

The problem with permanently filling it in is that you really can't go back.

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post #5 of 19 Old 09-23-2009 Thread Starter
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The primary issue I am trying to address is having only 3 inches of fiberglass in the keel between me and a sunk boat. The rest of the keel is encapsulated lead. A secondary benefit is the fact that I will be able to reach the bottom of the bilge. It's not that big of a deal to have a hefty magnet on board to retrieve things, but the possibility of punching a hole in the keel just 3 inches from the bottom is disconcerting. I am looking for a permanent and seaworthy solution to the hollow keel. I suppose that I could lay up layer after layer of fiberglass to build it up and provide strength, but given the depth of the bilge that will be difficult to say the least.
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post #6 of 19 Old 09-23-2009
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I personally and I think many others would love to have a deep bilge. Too many modern boats have a very flat bilge and a cup or two of water will spread very easily to lockers etc. I would leave it alone after doing the repairs needed. Filling it in will not be a panacea for future groundings or damage as they could occur elsewhere. If you do fill it in use foam of some sort with epoxy as a large epoxy pour will heat and crack leaving you with a result that is not very strong anyway when it cures too fast (exothern). But if you do damage in the future in the same area be prepared to dig it all out to effect a proper repair.
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post #7 of 19 Old 09-23-2009
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Are you worried about the 3" not being enough thickness to withstand a solid hit? 3" is a huge thickness. It shouldn't easily crack.

I don't know where your crack was or how big it is, but unless you fill in the hollow section with structural material, the main strength that you are getting is from the glass mat in the keel already. Filled material will impart some toughness, but really not a significant amount of strength compared to an unfilled resin. You need load bearing material, such as continuous mat or roving, instead of chopped fiber. Yes chopped fiber will give you some increase in strength, but no where near what it would be for continuous fiber.

You could lay-up cloth around the inside of the hollow area, but you really need to ensure a good bond, else the interface, between the new and old plies.

I still think that a structural foam, shaped to the internal dimensions is the way to go. If you want to add additional strength, abrade the inside of the hollow keel, wrap some glass glass cloth around around the foam saturated with epoxy, and shove it into the hollow area. The plies will bond the old keel to the foam plug and create a water tight seal and fill in the hollow and stiffen it.

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post #8 of 19 Old 09-23-2009 Thread Starter
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Thanks everyone! The bilge is over 3 feet deep at this point, so I'm not too concerned about filling in 4-6 inches of it. I also wouldn't expect it to easily crack, but one has developed. I haven't had a chance to really investigate it, as I had to leave the boat quickly after hauling out. I will definately look into the structural foam option. Otherwise, I will probably just repair the crack from the outside, clean the hell out of the bilge, prep it, and lay up a bunch of new layers of mat or roving to try and build up the inside. Thanks again!
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post #9 of 19 Old 09-23-2009
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why not repair the problem, reinforce the area to help prevent future problems and then put a piece of stainless mesh or something over the large void so that water could drain down, you don't loose the benefits of a deep bilge but if you drop anything larger then then holes in the ss mesh it doesn't fall into oblivion.
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post #10 of 19 Old 09-23-2009
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I agree with southshore 100%. A lot less work and expense too.
Brian
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