dumping bilge through oar power

Some cleaver sea kayak builders have used foot operated pumps for self rescue. they used off the shelf bilge pumps and rigged it to a foot pedal. I think that would be the way to go, You can move a lot of water this way, could even have one pump on each foot pedal (twice the volume). Or as suggested a battery powered pump (add weight). If you have the boat designed to keep as much water out with decks or covers, except for the crew positions, than you will not take on as much water as an open boat anyway.

Either way you will not have to stop to bail with a foot operated pump, it takes advantage of the rowing action and does not depend on any clever and unproven device. Keep it simple, buy off the shelf pumps and rig them to a foot pedal/foot rest device. If something fails you just replace it with another off-the-shelf part. A lot less work to build than your idea of a full length bilge chamber.

 

Dude, go troll somewhere else. There are two kinds of people: those who are part of the problem, and those who are part of the solution. You're clearly the kind of <removed> who wittingly tries to 'get people's heads to explode.'

Please, read post #53 above, and then go away.

 

Thanks very much for the considered response. I think you're mostly right, but I started this thread as a thought experiment because I thought newer materials (i.e. carbon fiber) might offer an elegant design solution that I hadn't seen and wasn't possible before.

This thread is also asking specific advice in a specialty sub-forum titled "Hydrodynamics and Aerodynamics." I still haven't had a response from someone familiar with the calculus of hydrodynamics. Oh well.

And while I see your point, my way is still (much) more effective than using a bucket. Both in energy (not needing to lift water + bucket all the way over the gunwale), and not needing to stop rowing motion. I'm well aware that a bucket / bleach bottle is the go to method. I'm trying to think of a better solution (especially as I'm designing a boat with a clean sheet of paper).

AK, the gate could be around 2"x4," sprung tightly enough to keep water out when closed (even if below water line), but sprung loosely enough that gallons of water pushed against it would let it swing open (away from escaping flow). If the bilge was made in a shape that narrowed to the exit, I believe you'd get some hydraulic benefit that would help this work. I'm imagining something metal, machined to close tolerances, and where the spring tension would be precisely made for adjustability. Could be any shape, really.

 

Well, this is the design brief. I want to build a hull in the computer that will have enough reserve buoyancy that even with the weight of the hull, extended oarlocks, oars, sliding seat system, misc gear, and my 220lbs, I can still 'get the boat moving.' That means only leaving so much room for water / open space when dry. I want to calculate that. I want to make it a little faster, a little lower (certainly in windage), and that means LESS seaworthy (I'm curious about applying a wave-piercing hull shape to a rowboat). So I'll be taking on more water, but if I've got a design which can shed it, then I can still go out in rough conditions (which I find fun).

As I've stated on the http://www.boatdesign.net/forums/boat-design/designing-fast-rowboat-14250.html thread, it's been a lot fun reading and learning all about rowboat design. Impressive as well, in that centuries-old wisdom has been proven difficult to surpass. New CAD/CAM software makes it easier to try, and I'd like to, so we'll see if I can pull off anything worthwhile. I still bounce back and forth as to whether I'll be able to get anything cool actually working.

 

Guys, let's please keep the threads here polite to all other members. Thanks.

 

Dcn,

water sloshing back and hitting a spring loaded gate is exactly the same as my water hammer thing except-

1. My device is enclosed in a carefully designed pipe so that the most energy is transferred to the water going out the gate and not being frittered away in slosh friction.

2. The spring in your system is acting as a hull brake any time it is open. The float valve in the hammer thing doesn't act as a brake. (you'd be better off putting the gate in the bow so the spring pulls you along) (just kidding, that doesn't work for a different reason)

A simple pump that discharges through the hull is far more elegant from a physics standpoint. Big bore, low velocity, short pipe run is best. So sump and pump and discharge near midship under seat. Sloshing water is really evil. Quiet water isn't nearly so bad. There may be some gains to be made in that department.

 

The seat movement , is lets say 1 foot.

By using a round flexible hose that had a simple foot valve , a pump would be created by simply running a roller over the flexible hose.

Perhaps a thin hose for minor slop , and a 4 or 6 inch hose for rapid emptying.

The roller could lift when no pumping is required.

FF

 

He/she wont like any of those ideas FF.

Very grumpy and rude.

Hard to help someone like that.

Despite my best efforts, he/she is unpleasable it seems.

What a waste of time.