Deck leak

[Gerry Cooper]

I have a 91 Hunter 433, ex Moorings which has a persistant deck leak approximately amidships and on the starboard side. Using a mirror and some acrobatics you can see the water leak once a panel is removed just above the U shaped settee. The leak tends to run down the vessel side to the stbd bookshelf. I initially thought the jib track was leaking and have subsequently removed it, resealed and replaced. The first rain since the exercise has the leak continuing. The strange thing is the leak doesn't appear until an hour or so after the rain starts which makes me suspect the actual place where the water is getting in is higher up on the cabin sides. It then takes some time before it soaks down to the eventual exit point.Has anyone else experienced a similar problem?

 

[KEN MATEJKA]

PRESSURIZE CABIN

Here's a little trick a wise old salt once shared with me and I have used it twice with great success on both my prior boat and on my new boat.You will need to get the following: a powerful leaf blower, a piece of plwood the size of your companionway with a hole cut in the middle the size of the blower outlet tube,tape, a bottle of dawn and a gallon bucket.---not much.Next, place plywood in companion way, close slider, and tape the slider edges and plywood edges as air tight as possible(you wont be able to make them completely air tight, but do your best), tape up hatches in similar manner and stick the blower into the plywood hole. Now, mix a pretty concetrated solution of water and dish soap. Turn the blower on which will pressurize the cabin---the stronger the blower is the better. Now walk around your deck and putting small amounts of the soapy water solution around all, and I mean all deck hardware. The leaking culprit(s) will have bubbles around them while the non-leakers will have nothing--bubbles will slowly form, don't expect to see a froth. I have done this twice with great success. The first time 2 screws on my port jib lead track were leaking. The second time was more difficult as I initially could not find a leak which was dripping into the aft berth, however, I was persistent and found the leak after removing the primary winch drum where 2 of the screws were leaking(bubbling). Anyway, give it a try it works. When you do find a leak, and you will, my advice is to use a polysulfide sealant as this will facilitate removal in the future if needs be.ken matejka

 

[Don Alexander]

DON'T PRESSURIZE

Gerry,I have heard this one before and it is extremely risky for the deck/hull joint and the deck itself. Someone said Hunters do it too.A leaf blower or a vacuum cleaner can generate up to 3 psi. Even a leaky setup like a boat hull might provide sufficiently low leakage so that 0.1 psi is developed. i.e. 1/30 th of the max blower pressure.Now your deck is 43' X 12 inches long and 14' x 12 inches beam.Allowing for 50% loss of area due to bow & stern shaping gives an area of 3,752,352 square inches.Putting this area at 0.1 psi gives a force of 375,235 pounds or 167.5 TONS or 10 times the weight of the boat.This will rip your deck off your bulkheads and part the hull deck joint.Then you will have a leak and you won't need washing up liquid to know where it is!!!!If an adjustable vent could be arranged so that you could gradually close it off whilst watching the deck balloon up then you might get away with it but the failure is likely to be sudden and catastrophic.

 

[Gerry Cooper]

Thanks for the input

I will try the cabin pressure method. It is puzzling that even after resealing the jib track water is still coming in from an area very near the track. My only other thoughts are the shroud deck fitting/thru deck, the cabin top handrail deck fitting or the mast safety rail to deck fittings.As it takes an hour or 2 for the water to actually leak into the cabin, is it possible that the water is soaking into the balsa core and only appears once the core is saturated?Thanks to all for the suggestion and advice.Regards

 

[Don Alexander]

An Apology - Sorry Gerry, Thanks Jim

Jim was right. My calculations about pressure were way out. I just repeated them and can find no way of getting the original results. Re-calculating but using the full pressure available from the motor still gives dangerous internal bursting forces on the deck so I am still of the opinion that this is a potentially harmful practice unless an adjustable vent or automatic pressure relief valve can be built.It seems that working at 2:37 am is not the best time for the brain.Sorry Gerry if I mislead you,Regards,Don Alexander