Water between hull & Deck

[Richard Taylor]

If this is a really daft question, then I apologise in advance.

I havent investigated this myself yet but would like to get some thoughts before I waste a lot of time taking things to pieces.

I seem to get a large amount of water between the skins. Because she hasnt had much use yet I dont have a lot to go on but the most obvious indication to me that there may be a problem is whenever I wash the boat down. I take out the bung and have to wait a number of minutes for the water to drain away. Is this to be expected? I am concerned that Im going to be hauling all this extra weight around all season. Particularly as I intend to leave her on a mooring for at least a month in the summer rather that pull her onto the trailer after every excursion.

Clearly the drain plug is there for a good reason, so some water is expected to accumulate, but Im concerned that something needs sealing up properly on my boat.

Should I expect to see the bases of the GRP console and jockey seats etc sealed with silicon to the deck (they are not)? The steering and electrics take a route under the deck so I imagine that it is here that the water is getting in.

Should I find more important things to worry about???

Rick

[Brian]

This is one of the proverbial true mysteries of life and the universe itself.

No matter how the decks are sealed, significant amounts of water ALWAYS gets in between the hulls.
Especially as you plan to leave your boat afloat, you must do the following:
-fit an auto-bilge pump between decks, draining overboard. Said pump must be perma-wired to the battery so it is always live. Then when a reasonable amount of water accumulates between the hulls, it trips the float switch and pumps it out.
-you may also like to consider fitting a long-screw, brass bung plug in the place of the (probably plastic) one you currently have.
-when leaving your boat afloat, try and cover its open deck area. This will reduce the amount of water ingressing in general
-in any case fit a further bilge-pump in the well area by the o/b engine. This will take the deck water overboard both at when rest and perhaps while underway, in spray or bad weather, and further help reduce ingress between hulls

[Aging Youth]

Hi Brian,

A couple of questions for you, based on what you have already said.

1. Do you recommend drilling through the deck and install a deck gland to seal the pipe work?

2. What size pump would you go for bearing in mind the height of the pump itself?

I have been told to go for biggest I can afford. Is this really nesscesary?

3. Last one. Are they very easy to install regarding the wiring up of conections? or should I leave it to the proffesionals?

Belive me if you have seen me with a srcew driver in my hand you would understand why Iask.

Regards

[Brian]

AY
My experience is based on owning a Zodiac 5.5 and an Avon 6.2 both of which took in water between the hulls. This despite a Poirot-like investigation by me and others that revealed "absolutely and categorically, no way water could get in".
In both boats I then got professionals to inset a proper, sealed, flush-mounted deck access cover near the rear of each boat and to install "suitable" pumps. One under the deck and one in the "engine-well" on-deck to clear rain and waves. Pl. don't ask me for details, I suspect I am even less technical than you. I seem to remember them being Rule brand pumps and not costing too much either. I think about £30 each from memory.
As for size and capacity-leave it to the pros. to advise. Size-wise they are quite small. Even on my Scorpion, the big b*****rs are only about 5 x 4 x 2 inches.
I can't quite see why you would need "serious" capacity pumps. Most boats have some form of draining facility on deck (elephant trunks, one way valves or whatever) and so should not need high capacity devices. You open up your throttles and deck water soon goes out.

[Aging Youth]

Thanks Brian,

My Humber has no deck well and only one elephants trunk on the port stern side.

I have already got the watertight hatch so it just leaves the bilge pump to install.

Many thanks.

[mojofilter]

my humble opinion

2 days in the water and the space between the hulls will be half full of water, 2 weeks on the trailer and not a drop of it will have drained out. this would lead me to believe that the water is coming in from above........however for the two days the boat was in the water there was no rain and it was flat calm, so no significant splashing, so where does it come from, who knows, its one of boatings mysteries.

I can only speculate that the pressure of the water pushing up on the hull, especially when bouncing through the waves is greater than gravitational force, thus forcing its way in, but not back out, through any possible gaps........however, the amount of water ingressed is always somewhat greater than can reasonably expected to squeeze through screwholes etc....

so this brings us back to square one, where does the water get in?, who knows.

anybody got any other ideas

smokinmojofilter

[Jelly]

Mojo
Thought just crossed my mind ( no rude comments please - it was perfectly lonely up there)

Test the water -
if its fresh its rain water, hence deck leak or
if its salty - that'll be the sea then - check the bungs / skin fittings.

if it tastes of fuel you have my sympathies - mouth syphoning diesel was one of my most stupid mistakes
Jelly

[jwalker]

Originally posted by Brian
No matter how the decks are sealed, significant amounts of water ALWAYS gets in between the hulls.

No it doesn't. Now Brian, no emotion, just be logical. If it is sealed, it is sealed. If water gets in, it is not sealed.


-------------------------------------------------------

mouth syphoning diesel was one of my... Jelly

I prefer meths myself.

[thanasis]

Please stop thinking of what you have to do to prevent water coming in between hull and deck. Always keep in mind that hull and deck are not rigid. When the boat hits on wave the air in the compartment between will be compressed and finally will find a way out. When decomporessed the vacum created will get air or water inside even of a very small hole that can be undedectable even if you fill the space between hull and deck with water under normal pressure. On my boat i have replace all the pumps with manual ones. They are more expensive than the toys that you usually find on the market but they work. Serius pumps usually takes a lot of battery. If you intent to use an electric pump go for one with a diaphragm that will not be damaged if you use it while there is no watter, which is a very common situation.

[Manos]

GIA SOU RE THANASI

Very simple and logical. I recon that your theory make a lot of sence

[jwalker]

Originally posted by Manos
I recon that your theory make a lot of sence