Thoughts on cockpit drains

[Sailtime]

Hi tophats

I've been thinking about the cockpit drains in my mk 1.. you can tell boat speed from water coming in the drains around 5 knots.. means you need boots which is fine or put some duckboards in to avoid the water.

But the internal diameter of the drains is very small and how efficiently they drain the cockpit in the event of a wave coming over the side or back i dunno..

What are opinions on alternative drain options? Out through the transom? Bigger drain holes?

Out the side?

Interested on thoughts.. there has to be a way to avoid the water sucking up..

Cheers

[Phillip]

Firstly,

"the internal diameter of the drains is very small and how efficiently they drain the cockpit in the event of a wave coming over the side or back"

In all the sailing I've done and from all the stories I've heard, I've never heard of a wave coming over the side or back of a Mk 1. Period. Spray yes but not a wave.

It took me some time but recently I discovered that Formit raised the cockpit floor of the Mk 2 & 3 100mm to overcome the water in the cockpit at 5 knots plus.
[mind you the 6 Mk 1s Formit produced have the same floor depths as Bakers Mk 1s do]

One of the reasons the water comes in is that when fully heeled the cockpit drain opening is below water level and there is also a bit of suction caused by boat speed.

What can you do about it? Not much apart from buying some boots or sailing at less than 5 knots plus, which over a long cruise rarely happens anyway.
To alter the drains would be a big job and to raise the floor also means raising the seats, an even bigger job. I had a thought some time ago about putting a rubber non return duckbill on the outlets, but when I considered the how they would attract barnacles etc I gave it away. As far as going out the transom there is a structural timber across there [for mounting an outboard motor] and remember the lower part will be below water anyway.

Hope all this helps

[Sailtime]

Good points Phillip but i still reckon there's gotta be a way to stop water back flowing up the drains.. I'm not interested in raising the floor or modifying the cockpit I'm just thinking drains..

As you say the main purpose is to clear small amounts of water out of the cockpit.. the amount of water sucking up increased when i gave the drains a good clear out of crustaceans that had set up at the outlet.. and its also not just on heeling - when motoring around 5 knots it happens so i think it's more a suction thing?

There must be a small one way non return valve somewhere that could be installed at the cockpit end of the drains.. would have to be slim..

I'll keep looking!

[Ianb]

You could try a small cowling in front of the outlet. A bit like a mini spray hood in shape. This will create a suction pressure when under way.

[Ianb]

To elaborate,the cowling can be a simple sheet plastic fabrication, just as long as it creates a negative pressure. You could also mould a more elaborate f/g shape from a ball the size of the outlet hole. A further possibility is to modify a standard ss through hull inlet strainer by cutting off the strainer bit and turning it to act as a suction rather than a scoop.This is probably the easiest.

[Phillip]

To elaborate,the cowling can be a simple sheet plastic fabrication, just as long as it creates a negative pressure. You could also mould a more elaborate f/g shape from a ball the size of the outlet hole. A further possibility is to modify a standard ss through hull inlet strainer by cutting off the strainer bit and turning it to act as a suction rather than a scoop.This is probably the easiest.

Have you tried this Ianb?

[Shaun]

That's good idea Ian, possibly one of those SS small cowlings or possibly something like this?

cowlingscoop2.jpg (3.33 KiB) Viewed 2548 times

[Ianb]

To elaborate,the cowling can be a simple sheet plastic fabrication, just as long as it creates a negative pressure. You could also mould a more elaborate f/g shape from a ball the size of the outlet hole. A further possibility is to modify a standard ss through hull inlet strainer by cutting off the strainer bit and turning it to act as a suction rather than a scoop.This is probably the easiest.

Have you tried this Ianb?

No, but it is basic engineering. I like the modified inlet strainer solution best. it is easiest to do. Attack with an angle grinder and mount the other way. It will cause an extra little bit of drag, but a big improvement on comfort.