Welcome Log In Create A New Profile

Advanced

Self Bailing?

Posted by Sandy 
Self Bailing?
April 16, 2008 07:30PM
How do the self bailing designs self bail? I am familiar with how a self-bailing raft works, but not sure with a dory. I see what I think are bailing holes on the bottom of the bow of some boats, but cannot figure out how the water moves uphill to get to the raised bow.

Is there a discussion of this in the Fletcher book?

Thanks,
Erik
Self Bailing?
April 17, 2008 12:51AM
The floor and drain you want to bail would need to be above the water line, even if just by a bit. I see in Fletchers book the Colorado River Dory has a drain in the rowers floor which is 6 inches off the bottom. I suspect the boat draws less than that fully loaded.

My question is, how much would it take to raise the floor in the front footwell to the same level relative to the water line so it could drain too? The book suggests that this has been done in some boats but it requires the seat to be raised as well causing the center of gravity to raise which in turn makes the boat tippy. I would like to have my cake and eat it too, so i'm trying to figure out the minimum you could raise the floor, and then just bump the seat 2 inches maybe so it does not get too high. One other option I have thought of is having an automatic bilge pump running off a 12 volt battery like in a regular boat. This would probably require too much plumbing and get away from the spirit of an oar powered boat, but maybe not. I need to figure out a slick way to handle this because my experience with big heavy oar rafts is that quick drainage is paramount. Usually if something fills my boat with water I'm in an area where I have to make some moves and nothing is worse than a boat full of water. I now have my raft set up to completely drain in less than 8 seconds which may or may not be realistic for a dory footwell. This is just one of the many things I now obsess about as I plan what I want to build.

Also keep in mind I have not built squat yet so the above information may be suspect.

Arlo
Self Bailing?
April 17, 2008 01:42AM
With my boat (a honky dory designed by Sandy), the water line runs along a point from the bottom of the stem to the bottom of the transon. It the boat is not loaded it will float a bit higher. I am in the process of making my boat self bailing. The floor needs to be raised an inch of 2 above this line. You can string a line inside from where the floor meets the stem in front and transom in the rear. Just keep the floor compartments above this line.


Self Bailing?
April 17, 2008 01:20PM
A couple of pictures are worth a........

The deck area is pitched to the foot well, which has a drain that exits the side of the boat...much like a sink

Additionally some boats have a scupper cut into the seating area which drains off some water taken on


Self Bailing?
April 17, 2008 03:10PM
This is what I did I took my boat onto a small pond fully loaded and added as many people as I could to put as much weight in it as I could. I then hopped in my kayak and measured how much the boat was drafting. I then removed the boat from the water did some measureing on land and marked my cut. I found these really cool purge valve at ACE hardware that have a rubber flap that seels when under presure from water, water can not go through the one way but flaps open from the other direction letting the water out of your foot well. I do not have a raised or sub floor in my foot well of either my rowers or passangers compartment. So My scuppers are about 8" on the outside of the sides and about 10" on the inside of the footwell giving it about a one and a half inch slope over a fourteen inch span. I still have to bail a significant amount of water. My Father Uses a bilge pump with a float switch and a manual switch with a dewalt 18 volt rechargeable bat. Its fast the plumbing is very simple all he needs to do is find a small solar pannel to recharge the bat durring a Grand Canyon Trip.
Self Bailing?
April 17, 2008 03:37PM
Hey Kyle,
That sounds amazing. Could you post photos of your setup? Especially the valve?

Also, all you people with false floors... Doesn't it make it difficult to repair since you can't get to the inside? Or would filling the void with foam give you the needed "flex" and thus prevent puntures?
Self Bailing?
April 17, 2008 06:01PM
It's not so much of a false floor like you are imagining, as just a framed in cockpit or footwell which collects the water that comes over the gunnels, the bottom of which is set above the waterline. On my boat, the cockpit floor is about 7-8" above the bottom of the boat, which draws about 5-7" of water fully loaded. The decks are slanted to channel most of the water from the decks into my footwell. The two hatches on either side of my cockpit are connected underneath the footwell, so I can get underneath. (That is where I store my cases of beer, and they are kept cold being below waterline.)

So, in my footwell I have a recessed cockpit drain (Perko) which connects to a 2" bilge hose, and a thru-hull scupper valve (like kyle described, also Perko) with a rubber flapper, which only allows water to travel out, not it. And even if I take on a ton of water and the drain goes below the waterline, it will still drain to the waterline, and won't take on any water.

I have a drawing I will try to upload if I can get it scanned...

Self Bailing?
April 17, 2008 06:24PM
Here is the ACE
and Product that I used. It is called a sump pump check valve. The part number is 4007548 and conects to 1 1/2" threaded pipe.
Enjoy Kyle



Self Bailing?
April 17, 2008 06:30PM
These are the parts I used. I ordered from go2marine.com, great service and quick ship.

Perko Cockpit drain - Part #51780
Perko Recessed Thru hull scupper - Part #86067

Sealed with 3M 5200 Fast Cure






Self Bailing?
April 18, 2008 01:29AM
Kyle,

Thanks for posting that image. I have been going craze trying to think of what off the shelf check valve would be available. I grew up near Philadelphia. Every house had a sump pump. I forgot all about them.

Great info.
Self Bailing?
April 18, 2008 01:16PM
If you want a completely different view of self-bailing dories. Look at how the surf dories do it. Wouldn't have all those nice dry compartments. For long trips would have to store stuff like a raft. But for mostly day trips would probably work out. Mark A

http://www.pearsonunlimited.com/DorySpecs.html
Self Bailing?
April 18, 2008 02:48PM
Good post Mark.

I have never seen these boats. One looks says it all. Floor at water line, water in over the top and out the sides through the holes in the side just above the floor line. Great images. The key to this is knowing the water line along the hull. Kyle seems to have said it best . Put the boat in the water load it and mark the water line. The rest is easy.
Self Bailing?
July 22, 2008 10:14AM
That's a nice looking boat Jeremy, and I wonder if I know your dad Steve? I'm curious about your discussion elsewhere of a boat by Derald Stewart with a 56" bottom. I knew Derald for a little while (not real well, just casual, but we did talk boats some) and at the time his boats were either 48" or 54" wide for the big Grand Canyon double enders. Anyway, you did a great job on Desolation!
Re: Self Bailing?
March 12, 2016 08:21AM
Any tried and well functioning self bailer valves available?
Re: Self Bailing?
March 12, 2016 01:00PM
Many of the posts above have my name (Sandy) attached as if I was the author. But I wasn't. This all happened when I migrated from one forum software package to another and I did it wrong. I need to switch forum software again soon. I'll try to make the data transfer run better the next time.

FWIW: my take on self bailing is different. I just run a 3" or 4" white PVC pipe straight down. When the boat is at rest in still water, if it draws 4" of water there will be approx 4" of water inside the pipe. So what? In big waves water will sometimes shoot up the pipe. But once again so what? That only happens in water so big waves are crashing over the bow anyway, giving you 500 gallon chest shots. A little water occasionally squirting back up a vertical drain pipe is insignificant.

Most of the time a wide vertical drain like that empties foot wells almost instantly. There is no better way to keep it dry. In my almost never humble opinion. Mechanical drain valves are like putting a petcock on your pecker. When you need to pee you need to pee.



Re: Self Bailing?
March 12, 2016 01:52PM
For valves, just do a search for scupper valve. They have a flap which will close when outside water pressure hits them.

As for self bailing, in really big rapids where you can go under water and totally fill the boat, we need to get the water out fast. Many of us have moved to pumps. I have 2 scupper valves to help dump water up higher along with 12 volt pumps to remove water. 300 gallons per hour works but I would go with 1000. Got to get water out fast so the boat continues to float high. Trying to maneuver a boat which sunk down to the gunwale with 1000 pounds of water is impossible.
Re: Self Bailing?
March 12, 2016 07:21PM
Yes a slightly curved up in the middle deck would drain a lot of water away from foot wells. Good idea. But you still need to drain the foot wells, no matter what. What diameter are these hinged flap scupper drains? I'll look that up. There are some photos and links in posts above this one.

Seems to me 3" is a minimum diameter. I saw one hand made boat at AJ DeRosa's wooden boat show a few years ago that was trying to drain foot wells with 3/4" inch flexible/bendable transparent tubing. That's not going to cut the mustard. You want the water to go out quickly.

My earlier talk about a vertical drain doesn't add up if, for instance, the front passenger well goes all the way to the floor, as it does in many boats. Mine won't. I'm building mine so the front passenger seating posture is more like the front seat of a car, where the legs go forward as much as down. That alone would make a floor in the front well a good 10" above the bottom panel. Because there is some rocker up front that would put the floor of the front seating well a good 12 to 14" above the water line. That's enough to make a vertical 3" straight down drain work just fine. That drain could--I suppose--have a hinged scupper flap in it if you wanted. I don't plan on doing it that way. I've been rowing over a 4" straight down drain and it it works just fine. Water does sometimes come up. But it goes right down again so fast you miss it if you blink an eye.



Re: Self Bailing?
March 13, 2016 03:25PM
I understand the idea of routing the water away from the footwell but,,,,,,,,,, there are times when you can't rout water any where. In the Grand Canyon I have been under water more times then I can remember. One example was getting taken into the wall at granite. After the mayhem was over I have no idea why I was still in the boat. The footwell was full to the top. The from area was full to the deck. Gravity was not enough to get that water out exactly as you pointed out. I had to ride an eddy for a while until I started floating again. The small 300 GPH pump up front was not big enough. I added scuppers above the pump outlet to help dump water faster. It needs the scuppers and a 1000 GPH pump. I filled the boat to the top at Tiger Wash, Granite, Hermit, Sockdolager, Lava, Upset, Hance. If the boat noses in a wave rolls over the deck an fill it up and that water has to be removed fast. A GC trip is about 16 days and small 10 amp hour batteries last all the way. There are new high power density Lithium polymer cells but I would think very seriously about using them. They have a huge discharge capability and if damaged or short circuited, they will catch fire. The also have a rigid lower voltage limit. Take out too much power and they will not recharge. So small SLA batteries are still the best solution and a 12 volt SLA batter in an ammo box which in not insulated properly is also dangerous. If it shorts to the box, it can melt steel.
Sorry, only registered users may post in this forum.

Click here to login