Cockpit Drains

[timday5]

My new-to-me 1976 E-27 (Hull #817) needs to come out of the water tomorrow. Last weekend, I discovered the cockpit drain thru-hulls (gate valves) were stuck open. That, plus the bulging hoses connecting the cockpit drains to them convinced me it was time to get her up on the hard and do some thru-hull replacements.

In planning my new thru-hulls / flanged seacock setup, a friend of mine asked why not route the cockpit drains to thru-hulls that are above the water line but lower than the cockpit floor. Sounds like a great idea to me - has anyone done this? I'm considering thru-hulls under the transom, thru the transom, or out the port and starboard quarters (all the way aft and outboard of the helmsman's seat). There seems to be lots of space in the transom lazarette - and outboard seems to be fairly well protected from everything that gets stuffed down there.

Any comments / warnings / notes /cautions on cockpit drain design would be appreciated.

 

[rwthomas1]

I can't comment on an E27 however here is how it works on my E38. The cockpit is T shaped and there are 4 drains. The two outermost drains are connected together with a T right next to the steering post and then a single hose leads down to a 1.5" thru-hull under the galley sink. The 2 inner drains lead out through thru-hulls above the waterline under the transom basically just aft of the rudder. The inner drain hoses are crossed. That is, the port drain empties starboard thru-hull and vice versa. The reason is to keep the drains from filling the cockpit with seawater when heeled over. Hope this helps. RT

 

[NateHanson]

The main thing to look out for is that you position them so they will drain at any angle of heel, and with short enough hoses that they drain quickly.

If you drain them out the quarters, outboard, they may be submerged enough when heeled that they fill the cockpit with water. Or if you cross them to avoid that, they could be angled up when heeled, so that they don't drain.

Inboard under the transom probably reduces these risks because heel angles won't be as much of a factor if everything is near the centerline.

 

[Captron]

Cockpit Scuppers

I'm pretty sure that the cockpit of our E38 won't drain very quickly if it were to get filled with water. The drains are adequate for handling rain or the wash water but not much else. That plus I'm not crazy about the idea of draining the cockpit under the galley sink. Even with that arrangement, the lee scuppers ship seawater when we're heeled over and that gets the cockpit floor wet. (maybe that's because we're so heavily loaded when cruising too) Umm, I could close the through hull valve, but have you seen what's under my sink? I suppose I'm basically lazy.

I've thought about eliminating the outboard drains with two larger pipes that would exit the transom. Maybe something on the order of 3 or 4 inches in diameter. Scuppers that big would empty most of a cockpit full of water pretty fast. I've never seen a wave reach the transom either but maybe a flapper could be arranged to prevent a large amount of water entering that way.

I worry though, that holes that large might compromise the strength of the hull especially given the loading of the backstay. OK, I suppose the backstay could be split to the corners of the transom but now we're talking major redesign type surgery. Also the propane lockers are in the way so the drains need to be routed around them. I suppose that's why I haven't done it yet, complications...

 

[treilley]

Rob, is that the factory configuration? My 35 has the inboard going to the seacock below the sink in the galley and the outboard are crossed to the transom seacocks.

I have always been curious why 1 pair drains above WL and 1 pair drains below WL. Anyone know what the theory is behind this?

 

[rwthomas1]

Rob, is that the factory configuration? My 35 has the inboard going to the seacock below the sink in the galley and the outboard are crossed to the transom seacocks.

I have always been curious why 1 pair drains above WL and 1 pair drains below WL. Anyone know what the theory is behind this?

I have no idea if my setup is factory or not. I say not as the bulkhead behind the steering post has been cut to pass the crossing inner drain lines. I also say not as Captron's setup ships water when heeled and mine does not. Ever. Having the outer drains connect to a T and drain under the galley sink made me nervous too however it will drain ALL the water even at the most extreme heel angle. My boat would have to be knocked down, as in mast level with the water for the outer drains to stop draining. They exit almost the lowest part of the hull.

Captron, how about a pic of your drains? How are they configured that they ship water when heeled? RT

 

[treilley]

I get water from my outboard scuppers when heeled bcause there is a lowpoint in the hoses that causes water to backflow into the cockpit. It is barely more than a wet spot around the scupper. No water comes in from the seacock. The water comes up from the lee scupper which is connected to the windward seacock that is out of the water.

Rob, I am thinking that your setup would prevent this as there is a more direct path from the inner scuppers to the seacocks and that there would be no low points to collect water.

 

[Captron]

Drains

I'll have to go study mine again. Two of the drains are Tee'd together and piped to a through-hull under the galley sink (I forget which two). The other two drain above the static waterline under the stern counter. I don't kmow if those two hoses are crossed over. I would guess that the lee side drain opening would be under water when heeled.

It's possible that the water in the cockpit floor is from a low spot in the hose althought at times it has seemed to be more than just a splash. Again it could be the loading of our boat. When we go on a cruise we're really low in the water although I think our fore and aft trim is pretty good.

 

[timday5]

Seems like if the outlet end was outboard of and lower than the drain when level, as the boat heels the leeward outlet would stay lower than the drain, since both are rotating around the same axis. At least until the boat was past 90 degrees of heel or so, in which case there are other issues.

That said, if the heel is such that the drain (inlet) is below the waterline, water will come thru the drain. But the same thing would happen if the drain led to a below the water line thru-hull, right? If the cockpit drain is 1 foot below water line, does it matter if the outlet is 6 inches or 2 feet below the waterline? (trying to remember my fluid dynamics here) :nerd:

Waves impacting above the water line outlets might drive water in, I suppose, but the amount of water should be pretty limited if the outlet ends point downward and are lower than the drains.

My plan is to route the drains to thru-hulls that are beneath the transom, above the water line, lower than and outboard of the drains, and not crossing the boat. This will let me use fairly short runs.

Then, once she's back in the water I'll take her out and get her heeled over (for the cause of science) and if water comes geyersing up through my drains I'll cross the lines.

I have to think that being able to close all below the waterline seacocks when the boat is unattended is goodness compared to having to leave them open to allow the cockpit to drain.

I'll keep everyone posted - appreciate the insights so far. This forum is awesome.

 

[Loren Beach]

Seems like if the outlet end was outboard of and lower than the drain when level, as the boat heels the leeward outlet would stay lower than the drain, since both are rotating around the same axis. At least until the boat was past 90 degrees of heel or so, in which case there are other issues.

That said, if the heel is such that the drain (inlet) is below the waterline, water will come thru the drain. But the same thing would happen if the drain led to a below the water line thru-hull, right? If the cockpit drain is 1 foot below water line, does it matter if the outlet is 6 inches or 2 feet below the waterline? (trying to remember my fluid dynamics here) :nerd:

Waves impacting above the water line outlets might drive water in, I suppose, but the amount of water should be pretty limited if the outlet ends point downward and are lower than the drains.

My plan is to route the drains to thru-hulls that are beneath the transom, above the water line, lower than and outboard of the drains, and not crossing the boat. This will let me use fairly short runs.

Then, once she's back in the water I'll take her out and get her heeled over (for the cause of science) and if water comes geyersing up through my drains I'll cross the lines.

I have to think that being able to close all below the waterline seacocks when the boat is unattended is goodness compared to having to leave them open to allow the cockpit to drain.

I'll keep everyone posted - appreciate the insights so far. This forum is awesome.

__________________________________

There is a factor that I do not see addressed in your thoughtful analysis above: That the outside "waterline" will be considerably higher at the rear quarter of the hull once you are: 1) at or considerably above calculated hull speed when reaching and running, and 2) heeled down 15 or 20 degrees driving to weather in a decent breeze.
This raises the true level of the outside water aft to sometimes just a few inches below the deck line for long minutes at a time. The low-side cockpit sole you are standing on *will* often back-flood. Not a big deal considering the fun you are having at the time (!) but it can get your new deck shoes all wet!

"Been there, got feet wet."


BTW, that's not just an Ericson thing, either. Any boat from the 70's or 80's with some IOR design influence in the stern sections will show the same symptom. Even my more-MORC-derived wider stern on the Olson will show a bit of this behavior... except that our cockpit drains exit at the back of the transom...

As someone else here often sez: Have fun and sail Fast!

Loren in PDX

 

[WhiteNoise]

I did that

Just ran that exact configuration on my 30+. I am going splash next week and will be doing the same test "for the sake of science". My theory is that, if you're heeled over that much then your boat is moving, thereby causing water to pass under the boat and under the thru hull, causing some level of suction.

At one point over the course of last season my thru hull for my sink drain became somewhat clogged or draining slowly. Enough that a sinkfull of water could sit in there for some time. I realized this as I was leaving for an evening sail and didn't have time to address it. I just left it figuring it would be gone by the time I made it out. Literally a minute after I began to motor out of the harbor I ran below to switch the battery to BOTH and the water was gone ... suction theory.

Additionally, my last boat was a Cataline 25 (I know, I know, you can all poke fun at will, haha) It had the same cockpit drain config. It also worked.

I'm pretty confident it will work.

 

[rwthomas1]

I have to think that being able to close all below the waterline seacocks when the boat is unattended is goodness compared to having to leave them open to allow the cockpit to drain.QUOTE]

FWIW, I also like being able to close the seacock and shutoff two of the drains when not aboard. The two remaining drains that empty above the waterline have no problem keeping up with rain. It works so I am not messing with it. RT

 

[timday5]

Just ran that exact configuration on my 30+. I am going splash next week and will be doing the same test "for the sake of science".

My boat will be on the hard for a while. If you have a chance, could you post pictures or a diagram of what you did so that I could blatantly copy your setup? Especially if your experiment is successful...

 

[timday5]

Update for those interested

Saturday, the port 1.5" thru hull defeated me. I got the plumbing except for the gate valve removed, but the thru hull would not rotate in the threads of the gate valve regardless of force applied. At one point, I had a steel prybar jammed into what was left of the tabs inside the thru-hull, and the steel prybar was bending.

Sunday I returned with 200' of 12 gauge extension cord, my reciprocating saw, and 2 6" rescue-demolition blades from Home Depot. From outside the boat, I was able to cut the thru hull into four sections (radial cuts outward, like a "plus"). I then was able to tap the sections out from inside the boat using a long, narrow pry bar. There was surprisingly little damage to the hull around the hole. Examining the pieces of old thru hull, I think that there was some sort of adhesive or sealant used, either that or someone had torqued the old gate valve onto the thru hull with significantly more force that I was able to apply with a 24" pry bar...

After the first 3 cuts, the first blade was pretty dull and started binding. As a result, the section of hull within about a foot of the hole flexed in and out with the saw's motion - reinforcing what I've read in this forum about always using backing for your thru hulls / seacocks.

The other two thru hulls were easier to remove, as the plywood backings were disintegrating. I plan to use seaboard http://store.hamiltonmarine.com/browse.cfm/2,762.html from hamilton marine as my backing for the new seacocks.

I also discovered that the starboard cockpit drain thru hull was stuck closed, not open, when black, stagnant water sprayed everywhere when I cut the hose off.

Good thing I had all those tools left over from remodeling my house...

 

[rwthomas1]

FWIW, please make sure that whatever the Seaboard is made out of is compatible with the sealant you plan on using. I know from experience that Starboard expands and contracts quite a bit and not much likes to stick to it.... RT

 

[timday5]

FWIW, please make sure that whatever the Seaboard is made out of is compatible with the sealant you plan on using. I know from experience that Starboard expands and contracts quite a bit and not much likes to stick to it.... RT

Oh - good point. After reading your post, I checked out the starboard web site FAQ. In answer to the question "what adhesives or sealants to use" they basically say you can caulk it, "some success has been achieved with adhesives" and ... we recommend mechanical fastening. http://www.kingstarboard.com/InfoCenter/FAQ.aspx. You probably saved me some serious frustration / wasted non-sailing hours.

 

[tenders]

I like Starboard a lot but for this application would stick to epoxy-coated marine plywood. It will last a LONG time.

 

[Loren Beach]

Backing plate idea

Since the ultra high-density plastic material, whether "seaboard" or "starboard" costs quite a bit, why not use something with the same coeficient of expansion as your FRP boat hull, like G10/FR4 epoxy board. (Lots more tensile strength, too.)
Comes in lots of different thicknesses, can be epoxied to the hull (of course) and will adhere to all the same sealants that the existing FRP hull bonds to.

We have used it for backing plates and reinforcements all around our boat. Any plastics company, like retailer TAP Plastics, will have it in stock.
Here in Portland, I can buy it from the remainders box in small pieces from a wholesaler, at their will-call desk. When I thank them for taking time for a nickle-dime customer, they just chuckle and tell me that I am not the only boater that comes in for project supplies...

Loren in PDX

 

[rwthomas1]

While I agree with Loren completely, GRP backer boards are likely the BEST possible material, they are much more difficult to cut and abuse saw blades, etc. mercilessly. The dust is also nasty, itchy, etc. Don't get me wrong, I love it and use it when I can however epoxy soaked marine plywood is the easy way out. Done correctly it will last a long, long time. This all depends on how much effort you want to put into it and how much skill you have. YRMV.... RT

 

[Emerald]

Something else that is worth looking at is epoxy coated MDO - medium density overlay. Just yet another choice to pick from