Self-draining cockpit

[KenMcCulloch]

A possible project for this winter's refit will be to buld a self-draining cockpit. This will have a number of benefits and I have a design forming in my mind that should do the job and will provide solutions to quite a number of minor problems as well as making the boat feel a lot safer in rufty weather. Maintaining ventilation to the planks and timbers that become enclosed will be a priority, and of course the drains would have suitable valves to prevent flooding in the event of pipework failure.

My question for the panel is this: What would people see as the pros and cons of two 38mm diagonal drains exiting through the hull planking on either side, viz-a-viz a single 51 mm drain going out through the transom?

The transom already has 3 holes that weren't part of the original builder's vision, and the starboard side in the general area has a shaft log for the offset prop, a water intake for the engine and a redundant sink drain that has been very carefully and effectively plugged. All of these are several planks away from where a drain would go, and the port side is pretty well virgin. I am beginning to favour the double drain myself and thinking that a further hole in a plank just above (?) the waterline each side is neither here nor there. I say just above because the planking on a Folkboat towards the stern turns right in towards the rudder post above the waterline and a cockpit drain should be quite effective there.

Ideas and experiences welcome.

 

[MasterofHera]

Hi Ken Hera is self draining. I will measure up tomorrow. There are 2 holes in the cockpit sole. Underneath they go into a Y unit for single outlet on Srbd/ side.I still have not fathomed out niceties of posting pics on here ...but could send them by email if you want. PM me if you like the idea.
Mike

 

[johnlilley]

I am sure you have considered the obvious, but is the cockpit sole high enough above the waterline for effective draining. Crossed over pipes will prevent heeling flooding but a transom drain can often lead to the cockpit sole being partly flooded when the stern in a bit low, either under engine or with a full compliment of crew, or if the drain does not fall from the sole height, a permanent puddle

John Lilley

 

[pyrojames]

If the lower corners of the cockpit go below the waterline when heeled then crossed over pipes will not help, unless the outlet rises above the water at the same time. This has the disadvantage that when heeled, excess water can not be drained from the cockpit. I prefer straight drains, that drain fast and always drain the cockpit water out to the dynamic waterline. Crossed over drains simply leading to existing hull fittings below the waterline will have no effect on cockpit heeling flooding.

 

[KenMcCulloch]

[ QUOTE ]
I am sure you have considered the obvious, but is the cockpit sole high enough above the waterline for effective draining. Crossed over pipes will prevent heeling flooding but a transom drain can often lead to the cockpit sole being partly flooded when the stern in a bit low, either under engine or with a full compliment of crew, or if the drain does not fall from the sole height, a permanent puddle

John Lilley

[/ QUOTE ]
John, thanks for that. The existing cockpit sole is below the waterline and part of the plan would be to raise it. As things stand the cockpit is so deep and the benches so low that things are quite awkward when heeled, which is one of the several reasons for contemplating this. I think you are right about the transom drain, the shallow and narrow submerged sections aft mean that crew in the cockpit lowers the waterline by several inches.

 

[KenMcCulloch]

[ QUOTE ]
If the lower corners of the cockpit go below the waterline when heeled then crossed over pipes will not help, unless the outlet rises above the water at the same time. This has the disadvantage that when heeled, excess water can not be drained from the cockpit. I prefer straight drains, that drain fast and always drain the cockpit water out to the dynamic waterline. Crossed over drains simply leading to existing hull fittings below the waterline will have no effect on cockpit heeling flooding.

[/ QUOTE ]
You are quite right. Of course the dynamic heeled waterline can be somewhere around the toerail on a Folkboat which would mean the drains would only work when heeled. Water in the cockpit is by no means a regular occurrence in a Folkboat indeed the whole approach to the design of the after sections is intended to minimise the risk of pooping. If crossed drains mean that allowing the boat to come more upright is necessary in order to drain the cockpit I can live with that, much less of a trouble than a hull half full of water and half an hour's pumping to get it out, which is what one might contemplate with the boat as she is.

 

[MasterofHera]

Hi there Ken and company. Went down to Hera this morning and this is what I found with her self draining cockpit. Outlets at front of the cockpit (2) about 3 in from each side. Internal diameter 1". They immediately change to 2" pipes .....then into a "Y" piece on the starboard side (still2") then about 12" of 2" to the Seacock. All pipework is secured with double hose clips.
I put a spirt leval on the cockpit sole and there was half a bubble of fall towardsthe outlets. Measuring the water leval in the outlets (water can be seen) it was about 5" with the seacock open. Blocked off the outlets with gaffer tape and put about 20gals in the cockpit. Pulled the tape off to let the water out.Very quickly back to normality. I did not measure the depth of the cockpit but it is obviously a lot less than Ken describes in Boarder Maid.

 

[Peterduck]

The idea of a deep cockpit being a good thing appears to be a peculiarly UK concept. In Australia, cockpit seating is at deck level, so that the cockpit sole is so much higher up. Self-draining cockpits with deck-level bridgedecks are considered to be a given.
Peter.

 

[KenMcCulloch]

[ QUOTE ]
The idea of a deep cockpit being a good thing appears to be a peculiarly UK concept. In Australia, cockpit seating is at deck level, so that the cockpit sole is so much higher up. Self-draining cockpits with deck-level bridgedecks are considered to be a given.
Peter.

[/ QUOTE ] Border Maid was one of the early Folkboats built in the UK to a Swedish design and mine has what some people call a 'Baltic' cockpit. I don't think it's a UK thing at all although there is a view that some depth in the cockpit reduces the risk of being thrown out in rough conditions. We have a lot of those /forums/images/graemlins/wink.gif

 

[pyrojames]

This always struck me as slightly odd. Most of my Australian sailing was offshore in the Pacific where both sea state and swell was nearly always greater than it is in the North Sea, and mostly than it is in the channel. Moving south from Sydney into Bass Straight and the Southern Ocean, was another step up again, something that even the North Atlantic only achieves occaisionally.

 

[ValleyForge]

The dragon fleet sailed in Sydney harbour have converted to self draining cockpits - having raced there the swell from the traffic has to be seen to be believed ... (& the waters warm too, but still as wet) /forums/images/graemlins/wink.gif

 

[calloo]

Hello Ken This thread is very interesting to me for I am proposing a similar project this winter ie 09/10. Would you be kind enough to tell what conclusion you came to. In my case I plan to enclose the cockpit well with detachable boards and put the drain in the seat, thus increasing the distance to waterline and thereby reducing the available volume when pooped. My idea is to protect myself from the effect of pooping when the series drogue is deployed. I sail in North Scotland and like to venture into North Atlantic waters such as Faeroes where the risk of bad weather requires a lot of consideration.

 

[KenMcCulloch]

Hi
I eventually decided to leave things as they are for now. I have worked out a sketch plan for sealing the cockpit and making the swampable volume about 40% of what it is now, involving about 5m or so of 2"x4" hardwood for framing and a sheet of 18mm ply, with a dedicated bilge pump and bucket to empty any water out. I will implement this plan in the relatively unlikely event of a trip to Lofoten or similar.

 

[lesweeks]

Self-draining debate

I've also found this an interesting topic as I've a completely blank canvas as far as the cockpit of my restoration project is concerned; I'm just planning how to install the rear cabin bulkhead at the moment and so I guess it's the ideal time to plan a self drainer - if that's the way to go.

I've been through the shall I, shan't I so often I'm almost giddy! I intend having the sole over the engine, if possible, so that suggests that it will be above the waterline. The photo shows the pre-stripped area with a 'witness' line showing where the sole once was (there's three of them!) and probably about the height I'll settle on. (Yes, those seams are very wide, but that's another story).

So, if this isn't an unacceptable thread drift what are the cons of a self drainer?

 

[KenMcCulloch]

.

So, if this isn't an unacceptable thread drift what are the cons of a self drainer?

I think the main or biggest argument against is the lack of air circulation leading to moisture levels conducive to rot in the areas enclosed by the cockpit. If you create nice big lockers under the seats you will then fill them with stuff which further inhibits air flow.

 

[Tranona]

Tranona has an open cockpit and I too have been through this process. Biggest difficulty for me is raising the sole high enough to get a reasonable fall. In 30 years I have never had solid water in the cockpit - but have never been out in much above a force 6. The stern is very bouyant which helps. One of the advantages of an open cockpit is that any water shipped gets spread throughout the boat rather than being concentrated in the stern. If you have good pumping you can deal with the water.

The downside to me on a wooden boat is keeping the cockpit "watertight". Many of the boats I am familiar with (Golden Hinds and Eventides) suffer from rot in the cockpit and main bulkhead areas from freshwater getting past joints. The solution to this, as on my boat, is a waterproof cockpit cover. Cheap and long lasting.

So, on balance, unless your design is prone to taking on water in the conditions in which it is used, I would stick to an open cockpit.

 

[old_salt]

Hi Ken. This might be of some help possibly a lot more than you wish to go for, as you can see it can get quite complicated the further you go.
The locker seats are in them selves self draining with over laps at the front and sides the slots for the drainage from the back of the seat fore and aft is there too.
We have an added problem in the cockpit a system of air passages and shutters in the cockpit gunwales as the engine is air cooled but that has some benefits we can run it at any time in the water or out.
I hope you find these pics interesting and may be of some help.

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[Simon_and_Tanja]

Self Draining?

Hi
I eventually decided to leave things as they are for now. I have worked out a sketch plan for sealing the cockpit and making the swampable volume about 40% of what it is now, involving about 5m or so of 2"x4" hardwood for framing and a sheet of 18mm ply, with a dedicated bilge pump and bucket to empty any water out. I will implement this plan in the relatively unlikely event of a trip to Lofoten or similar.

A wise decision I believe. Our Stella has a self-drainer retrofitted, with crossover drains exiting in the tuck port and starboard. The sole however is not high enough for this to be truly effective (2" above wl) and I assume the dimensions are pretty similar to your folkboat. The cockpit drains are good for draining rainwater when moored up (no cockpit cover) but when sailing I close the cocks to stop seawater slopping up the drains and cooling my feet. Inevitably when heeled there is a beam-on sea running and the crossover is aranged such that water slops up (down in really strong winds ) the windward drain and into the cockpit.