Non Return Valves for Cockpit Drains

[bob_tyler]

Having had a new Beta 13.5 fitted to replace the Vire 7 in my Invicta 26 I have a small problem as the boat is considerably faster under power..

When I tried the engine flat out, after a gentle but variable revs running in period, I found that my cockpit drains let water uphill into the cockpit as the bows lift and the stern squats. The drains slope from the cockpit sole in a straight line, sloping downwards and out through the tramsom. They are glass fibre tubes, about 1½ inches in diameter moulded into the hull.

I fitted flap valves externally in the winter - the rubber type that external water pressure should hold shut. They have reduced the ingress but not eliminated it.

The exit holes in the transom are normally above the waterline but obviously dip below at maximum speed.

Any suggestions? The only solution I can think of are plugs at the inner end but this would look very untidy and rather defeat the self-draining cockpit. Being me, I would probably forget to remove them on going ashore and the cockpit would fill up with rainwater by the time I next went afloat. (A bit like launching a dinghy without putting the bung in! I'm sure we've all done that)

I don't believe that it is a weight problem as, when moored, the stern is no lower than before, just a problem at speed.

Help please! /forums/images/graemlins/smile.gif

 

[Stemar]

Judging by all the cr@p that accumulates in my cockpit drain strainers, I reckon that no non-return valve would stand a chance.

The expensive solution would be normal open solenoid valves that shut off the drains when the engine's running

You could try slowing down to your previous pace...

No, I wouldn't either! /forums/images/graemlins/smile.gif

Get a bigger anchor? /forums/images/graemlins/wink.gif

 

[mainmarine]

try Polymarine: http://cat.polymarine.com/ their self bailers may fit into your drains
Malc
Mainmarine

 

[alahol2]

You could try perspex flaps held against the transom with bungee cord up the drainpipe. Similar to those used by racing dinghies.

 

[Mirelle]

Does this nice bronze fitting, for traditional boats, made in the USA suggest a way of solving the problem?

 

[steve28]

When you do find the ideal solution can you let me know, im fed up having wet feet.


steve

 

[adelaidem]

i have seen cockpit drains that have ping pong balls in them that seal at the top when the water rises maybe this arangement will help.

 

[cagey]

similar problem few years ago show you my basic solution if you want in Falmouth Yacht Brokers give me a ring if you want
keith
sent no in pm

 

[bob_tyler]

Thanks for the suggestion, Mirelle, but these would fit horizontal outlets whereas mine are vertical

 

[NigeCh]

Your cheapest (and simplest) solution is to have tapered wooden bungs on lanyards next the outlet holes. When you want to motor you just push them in. When you stop motoring you take them out. KISS

OK, you've already suggested this but rejected it as it is an 'untidy' solution. You've just spent several thousands of pounds on a new oversized/overpowered engine and nobody told you that your stern would squat.

With respect, you don't need full revs. All that the extra power is doing is trying to push you uphill. If you take a GPS and measure your boat speed against rpm you'll find that your boat speed will not increase beyond a certain revs. I'd say that it would be between 1/2 & 2/3 your throttle setting. At that setting you won't be getting water backflowing into the cockpit. Beyond that setting all that will happen is that the stern will squat more and more with no increase in boat speed ... but more water flowing back up into the cockpit.

Get some bungs and really untidy lanyard. With really untidy lanyards you won't forget to take them out when you go ashore /forums/images/graemlins/smile.gif

 

[jon]

Sounds interesting,don't leave us in suspense!!

 

[bob_tyler]

I certainly see your point about revs and speed. However, the purpose of fitting an oversized engine was to allow me to punch against a headwind when combined with tide if I need to. If the extra power is going to counteract headwinds it is worthwhile. I use about 2200/2400rpm in normal cruising and the maximum revs available are about 3200. I chose the Beta 13.5 over the 10 just for this purpose and it has certainly been worth it as both engines are the same weight.

I prefer to use sail where possible but tacking direct to windward against the tide as well is frustrating when, after about four tacks you are back where you started - thats when the power is used both in light and stronger winds.

Although the flow back through the drains does help to keep the cockpit sole beneath the teak grating clean, I would prefer to chuck a bucket of sea water down now and again - wash it when I want to!

 

[bob_tyler]

I will certainly post the results on this forum. I get rather frustrated when threads are incomplete with no feedback on the eventual results, as the information could be useful to other forumites.

 

[Scarboroughsloop]

One other concern of mine would be your exhaust oulet. If the water is coming into the cockpit then your outlet may also be under water.

 

[bob_tyler]

Thanks for that but it is considerably higherand with a nice vertical loop and a Vetus Water Trap. Pretty safe.

 

[Guest]

No increase in speed ????

Design Hull speed has no stop limit in fact .... my hull is as most yachts about 6 kn hull speed ........... please then explain why this last weekend a speed of 9.8 kn was measured AND witnessed, allowing possibly 1kn current with us - that gives 8.8kn STW ......

My engine is a 4107 in a 25ft Motorsailer .... previous was 4-99 and that regularly pushed me over 7kn.

I have the water in cockpit problem at anything over slow speed ... and have valves fitted in drain lines ... that have to be closed / opened manually. I would be very interested in a solution .... but tend to mistrust one-way or non-return valves ... as like most drains - crud etc. could cause it to stay partly open ...

 

[bob_tyler]

Re: Non Return Valves for Cockpit Drains- THE ANSWER

[ QUOTE ]
try Polymarine: http://cat.polymarine.com/ their self bailers may fit into your drains
Malc
Mainmarine

[/ QUOTE ]

I promised to pass on the result.

I obtained 2 Dinghy self bailers from the above. They are circular and made to fit 35mm dia holes. My cockpit drains are 40mm plastic pipe.

I wrapped self amalgamating tape round the bailers and, when they were a very tight fit, tapped them gently into the end of the pipes.

Then fitted 3/4in no 6 stainless screws in the holes provided just as a belt and braces measure to ensure that external pressure does not force them out. Very unlikely I know.

Now have a dry cockpit sole (when its not raining) and water drains out OK. I chucked in a couple of bucketfuls to make sure.

Thanks to all for your helpful suggestions. /forums/images/graemlins/smile.gif

Bob

 

[Guest]

PLEASE post later a new thread ...

After a period of trial and use .... can you post a 'users' report on success etc. I am very interested to see if this will answer my problem ....

/forums/images/graemlins/cool.gif

 

[bob_tyler]

Re: PLEASE post later a new thread ...

Yes, I'll do that. They are a very simple fitting which can either let water out or in, depending which way round the rubber flap is fitted.

I bought two spare flaps in case. I would imagine that cigarette ends might have a problem getting through but normal refuse shouldn't be a problem.

They are very cheap, £2.10 + VAT each so an experiment would not be expensive.

Bob

 

[bob_tyler]

Re: PLEASE post later a new thread ...

Nigel,

Had a trial today. All working fine until suddenly water started coming in again at over 5.4kts (on log and GPS which agreed - top of tide).

I found that the starboard one had popped out of the pipe! There must be quite of bit of pressure there. The port "valve" was showing no signs of leakage.

I had secured the port one with 2 stainless screws through the holes provided but, as I had been doing quite a bit of drilling with my battery powered drill and it had run down, I was waiting to screw on the starboard one. It was only held by an interference fit by the tape which I had wrapped round the outside to seal it in and bring it up to 40mm dia. I thought that this would be enough but not so despite the fact that I had tapped it in quite firmly (or so I thought /forums/images/graemlins/frown.gif).

Will report again,

Bob