water leak

edmorales · Post by **edmorales** » 17 Jan 2004, 13:14

i noticed a slight leak coming from the bolt that holds the keel to the keel trunk. i want to try putting a dab of silicon sealant around the bolt's head/neck before installing. since the rules say that the keels must be removable, i'm just curious, is it allowed to add a non permanent seal on the keel trunk?

ralph kelley · Post by **ralph kelley** » 17 Jan 2004, 15:16

I would think the key questions would be:
(1) can the keel be installed and removed (A-yes, since the adhesive/sealant is not permanently bonding the keek to the hull)
(2) is the keel weight still within the limits (A - yes, no change in the bare keel weight)
(3) is the total boat weight at the minimum (A - yes, since any grams of adhesive is added to whatever is an otherwise legal total weight.

If I were measuring the craft at an event, I would not see a problem.

Ralph

Roy Thompson · Post by **Roy Thompson** » 17 Jan 2004, 21:02

I think most event measurers wouldn't even notice a blob of sealer around the keel fixing bolt - well done if you look out for it!
Ralph has covered the main points in terms of
measurements/rules etc, although see my point * below, but where is the water coming from? If it enters from below, ie. where the keel enters the trunking below the waterline, and rises up to the fixing at deck level due to the pressure exerted by the water as your boat flies thru the water, then you may consider trying something similar at the bottom end where the keel enters the trunking - *be careful, not to add any non-legal materials though. I have had the same problem on my IOM at the keel fixing bolt and resolved it with a blob of blue-tack on top of the bolt (that sticky blue stuff used to hang up posters temporarily). It doesn't affect the ability to remove the keel at all but I am still concerned that I have such a bad fitting keel/trunk below the water and that the trunking must be filling up with water for it to be forced out of the bolt hole at the deck. It may be with flexing of the keel/trunking/hull that the water enters under more pressed conditions, because on dry land it certainly isn't obvious how so much water gets in to the trunking. If you remove the keel immediately after a days sailing, is the trunking full of water or very wet? I guess it's normal and no cause for concern if we're not talking of more than a few cm3/grammes of water.
Makes you think doesn't it?

Steve Landeau · Post by **Steve Landeau** » 17 Jan 2004, 22:16

If you ever want to fix the leak properly, I would not suggest using silicone. Once you use it, it will be hard to get a clean surface to permanently repair the problem. I am always very hesitant to "temporarily" stop a leaking trunk because it cannot be reached to clean properly when it comes to the proper repair. Let's look at the problem: the trunk usually has a flat surface at the top that mates to the flat underside of the deck. If these separate, you can get water either through the hole for the keel, or around the mast hole if it is a keel stepped mast. The proper method to fix the keel hole is pretty simple. Using a dremel, carefully grind away the deck around the hole approx. twice the diameter of the hole. Try not to go through the keel trunk material. Once the deck area is gone, wax the keel and bolt and install it in the boat. Mix up some epoxy with milled fibers, making sure it is not too dry (thick). Fill the area you have ground away, and put the nut on with an oversized washer to apply pressure to the repaired area (making sure the washer and nut have wax on it too). This will cure the problem if you have a good fitting keel. If it does not fit the trunk well, it may be adding excess stress on the bolt. The bolt should not be holding the keel from moving around at all. It should only stop it from falling out.
Hope this helps,
Steve

Roy Thompson · Post by **Roy Thompson** » 18 Jan 2004, 10:48

Steve,
I was assuming that the process of 'gap filling' as you suggested had been done below the water already (probably by the builder during keel fitting) but hadn't thought about doing it at the top end. I also wouldn't have suggested silicon for the same reasons and would attack the problem at it's origen by trying to stop the water getting into the trunk in the first place. Without knowing more about where the water enters it woud be difficult to gaurantee the solution. On my home made cedar planked IOM, with carbon keel and fibreglass trunking, I sealed the lower end of the trunk/keel union as normal but at the top end (where the kell bolt goes) I turned the hull upside down and filled the top of the trunking with approx 5mm depth of epoxy + fibres before putting in the pre waxed and slightly reduced size (at the top) fin. This had the benefit of providing the perfect match between trunking and fin at the top as well as already having it at the bottom, as well as reinforcing the zone where the keel bolt is screwed down (we always tend to overtighten it I guess) and finally, helping to seal the trunking to underdeck join (from the inside) even better.
Whilst doing all of this it must be remebered to keep a careful eye on fin alignment, maximum draught, bulb inclination (if fixed) etc - it is far too easy to change something although if your fin is already fitted and you don't overdo it with the dremel giving a lot of play, then it shoudn't be a problem. If you are doing this during construction, it would be best to make up a jig to keep everything aligned as you want it.
In the end, my IOMs trunking always seems to be a little wet inside after a days racing, but as it doesn't semm to be more than a few grams water, it probablydoesn't mean there is a weight penelty. I know that my fin is more flexible than most and it may well be that when hard pressed it alows water to enter from below. On a previous all wood hull and keel, I did use silicone sealer around the hull/keel join and had no problems cleaning it because it was outside not inside - no doubt it didn't do much for the water flow in this zone though!

rÃ©mi brÃ¨s · Post by **rÃ©mi brÃ¨s** » 22 Jan 2004, 19:51

if problems with silicin sealent, try white pretroleum, for the same effect, ans easily removable

Steve Landeau · Post by **Steve Landeau** » 26 Jan 2004, 03:52

VCmeasurement wrote:Steve,
I sealed the lower end of the trunk/keel union as normal but at the top end (where the kell bolt goes) I turned the hull upside down and filled the top of the trunking with approx 5mm depth of epoxy + fibres before putting in the pre waxed and slightly reduced size (at the top) fin.

I have used this method to great success myself, but did not feel comfortable trying to explain it. Permanently gluing in the keel is a bad thing!! (almost did it just the other night on someone elses boat!). It is a great method to fix a leaking trunk, but great care must be taken to ensure the keel comes out when you are finished....

edmorales · Post by **edmorales** » 26 Jan 2004, 09:29

Steve,
Do you use a jig to prevent movement of the keel or to ensure that the bulb cant is in the correct setting while the epoxy/resin cures?

regards
Ed

Roy Thompson · Post by **Roy Thompson** » 26 Jan 2004, 17:31

Roy said

Whilst doing all of this it must be remebered to keep a careful eye on fin alignment, maximum draught, bulb inclination (if fixed) etc - it is far too easy to change something although if your fin is already fitted and you don't overdo it with the dremel giving a lot of play, then it shoudn't be a problem. If you are doing this during construction, it would be best to make up a jig to keep everything aligned as you want it.

That's what I do, I think it's vital. It's worth spending time making an accurate jig, correct fin and bulb allignment are vital to good performance.

Steve Landeau · Post by **Steve Landeau** » 26 Jan 2004, 22:25

edmorales wrote:Steve,
Do you use a jig to prevent movement of the keel or to ensure that the bulb cant is in the correct setting while the epoxy/resin cures?
regards
Ed

Jigs make alignment of the keel trunk very easy during original construction, but if the fit is proper, no jig is needed to repair a leaking trunk. Putting epoxy in the trunk, then installing the keel as normal (but well waxed), and allowing the epoxy to migrate into the leak will not affect the original alignment.

edmorales · Post by **edmorales** » 27 Jan 2004, 10:45

i checked the innards of my hull by dropping my digital camera inside after setting the timer to 10 seconds. i was able to get a clear idea of what was under. i noticed that the pair of shroud attachment points forward of the ones that i use, had their securing nuts loose. i was able to turn them by hand. with the aid of an rc car tyre cross wrench i was able to tighten them, then added a spot of ca. these attachements are forward of the original side stays which were (still) tight. i see it as another point of water ingress when the boat is well heeled. from an earlier photo of the boat, i could tell that it was just added. this made me think of checking all the attachemnet points for integrity (jib pivot points, back stay)

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