35-2 Thruhulls? Hose runs?


Member II
I'm trying to clean up the hose runs and cockpit scuppers on the 35-2 in rehab and wondering where the hoses connect. The P.O had everything connected to 1.25" drain close to the keel just behind door that accesses under the cockpit.

Can you kind folks offer some clues as to how the 4 drains connect to one or more thruhulls? I have 3 thruhulls under the cockpit - two on the starboard side and just off centre - ( a little to port). I'm not sure if this is original or if there have been some modifications.

thanks again for your help/




Member III
Might be similar

Look at the E381 Plumbing drawing in the Specs and Documents section. The drain lines are shown and may be similar to your situation.


Member III
E35II Scupper Drains

The (2) Port and (2) Starboard Cockpit Drains are tee'd out thru 1 1/2"
Port and Starboard ThruHulls located in front of the exhaust lift station,
behind the Salon Stairs. The Manual Bilge Pump exits out the Transom.
The Galley sink also tees in to the Starboard Cockpit Drain ThuHull.
There has been MUCH discussion about the SAFETY of having ThruHulls
for Cockpit Drains below the waterline. As you can Drain out the side of the
hull below the cockpit, I would survey that Design Change and verify that
you can Drain out by gravity.
Use 1 1/2" Drain Hose throughout and provide valves at each ThruHull.
When I leave the boat I CLOSE all ThruHulls.....but I have to leave these
Cockpit Drains open in case of rain :cool:
Never really liked the idea of draining the Cockpit below the waterline :nerd:

Let me know as I can be of further help on the E35II.
This is the start of Year #4 for my ReBuild Projects.

Good Luck to You :egrin: :egrin:



Member II
Onward with Drainage

Thanks Bill...I printed the E38 plumbing diagram. Good to see the layout - Mine will be something like that.

(Dan...thanks again. ...for the motivating picture - Nice Job! - Seems that you are a couple of years ahead of me. As in the past - I'll be taking you up on your offer of help and advice)

Now for the rest of the cockpit - re-sole and scuppers. The original drain tubes are 1.25" glassed in brass tubes. These have cracked off and will be replaced when I do the floor in the sping. I'm looking for a flushmount
plastic drain tube...any hints?




Sustaining Partner
flush mount thru-hulls, either bronze or Marelon would make for excellent drains! Simple to put a hose barb on the back side or an elbow if needed. The only drawback would be the lack of a screen to keep small objects from going for a ride. This could be easily remedied with perforated stainless or sink drain screens either cut and surface mounted with screws or epoxy. Just a thought.... RT


Member III
Scupper Drains

Check out the Scupper Drains in www.forespar.com :nerd:
Download the Catologue for all kinds of parts you will need to complete
your project. Marelon is great tuff stuff.


Member III
Has anyone come up with an alternative plumbing. I don't like ANY through hulls below the waterline, but there appear to some necessary evils - engine colling, head intake. But seems like cockpit scuppers and sink drains should drain some other way. Particularly problematic since I usually winter in the water. If left open, and a through hull or the hose connecting to it freezes and cracks, could sink her. If left closed, backs up and freezes solid in the cockpit bathtub; and dilutes out the anti-freeze I put in the scupper hoses, so could split them anyway. Any solutions?

I'm in the middle of a re-fit and would like to solve this - advice?



Member II
moving thru-hulls

Steven, like you, - I'm still considering moving the thru-hulls - but I don't want to mess with the drainage. Any other opinions or engineering tests.


Bud H.

Member II
Another wrinkle

My boat is in the water all winter also and while Eastern Washington is a desert we do get a fair amount of rain in the fall, winter and spring. One year I had the bright idea of closing the trough hulls for the exact reason you mentioned. What if the hoses freeze and break. Well, I went out to check the boat one Saturday after a week of rainy weather and was amazed to see the galley sink full to within a 1/4” of the rim!. Then it dawned on me, closing the trough hulls made the rain water that went down the scupper back up into the sink. A rainier week or a longer period going by without checking the boat would have made a "<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com
Hull</st1:City></ST1:pl” of a mess.

Another thing to think about with these drain hoses is the one from your sink to the tee in the through hull. Not so much the hose but the connection to your galley sink drain. Last year I had to replace the galley faucet and in order to do that had to take out the sink. When I went to disconnect the drain hose the strainer bib or tit or what ever you call that part under the sink that goes into the hose broke of in my hand. Totally corroded away. If that was to brake during an unattended period for the boat, and if there was enough water in it to overcome the permanent bend in the hose you could get a lot of water in your boat real fast. If you’re like me, it’s just one more thing to keep you awake at night.


Member III
Have similar problem with the sink. During the winter, after every major rain/snow event, I open the through hulls, drain the cockpit and sink, close the through hulls, then pour new anti-freeze into the cockpit drains until it backs up into the sink. Guess I could have been plugging the sink drain to prevent backup, but didn't think of it.

I'm now thinking I'll drain the sink to the shower sump, then just pump it out same as shower drainage (and maybe I'll take the ice-box drain also to the shower sump - it's not sanitary draining to the bilge). But that is not a good solution for the scuppers.


Sustaining Member
Drains above the water line

The drains can be ran above the water line< but must be done as follows or there can be problems when sailing: Tee the lines from both cockpit sections together (fore and aft) with the tee located below the aft scupper. then run the third hose across the boat th a thru hull as close to the waterline as possible. Don't forget the gate valves! The theory here is that as you lay one tack the thru hull for that side is in the water. That poses two problems. First water will drain faster into air than water so draining out the high side will compensate for only having one thru hull. Second if you are over hard the water will back up into the lower drain, by crossing the drains as the thru hull is lowered into the water the scupper is raised so the water doesn't back up into the cockpit. and the gate valves will be needed if there is ever a plumbing problem at sea as one drain will always be in the water on a tack. The reason to run the drains aft is that you want them fairly close to the center line and there is some hull below that is out of the water behind the rudder post. I would shoot for a spacing about the same as the originals. If you do this in the water, a word of caution , the hull sits lower in the water with someone back there drilling holes than it does with the driller carefully measuring the precise location the drains will be out of the water! Haven't made this change to mine yet but it is on the list. hope it helps, good luck.:):egrin:
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Member III
Replace Gate Valves !

As you install ANY new plumbing you have two options :cool:
1. Change old Gate Valves to Ball Valves using the existing ThruHull stem.
This can be done in the water (carefully :nerd:) on sound stems.
2. Replace Gate Valve ThruHulls with new Flanged Ball Valve ThruHulls.
This is the ultimate upgrade to insure the safety of those 1 1/2" holes
in your boat below the waterline :) Needs to be done on the hard.

In any event....do not leave those Gate Valves in your boat :nerd:
Get rid of them to sleep easier at night.

Happy ThruHulls :egrin: :egrin:


Member II
That reminds me....

Dan's post reminds me that it seems to be my job here to display how things should NOT be done. :esad: By example and the work of the PO.

Here are some snaps of plumbing that was leading to thru hulls...and remember that all the valves were frozen. So out it comes.

(note the hose barbed PVC fitting wedged into the ball valve. - and the condition of the hoses...)

all will be made right...!

all the best




Member III
Thanks for the reminder on ball valves. My last boat had gate valves that literally crumbled. Fortunately replaced them as you describe without mishap. Indigo scuppers go to thru-hulls that have ball valves that appear to be in good condition.

But the engine water intake thru-hull is protected by an in line valve. The valve looks fine but the handle is soft from corrosion. The manufacturer appears to be Honeywell-Braukmann. Can handles be replaced or should the whole valve be replaced? I think the valve is brass - it is not normally under water, but it is in the bilge so it gets wet -- is it worth replacing with bronze?

Fully Ported Brass Ball Valves for most heating, plumbing and industrial shut-off applications. The B200S valves have increased agency listing approvals as well as an enhanced design for increased solderability and longer


Member III
Replace that Old Valve !

Replace that questionable ball valve with a Full Port Bronze Ball Valve.
These valves are common Plumbing Items available at your local HD or
Hardware Store. Verify that the valve is Apollo or Crane Bronze 300 PSI WOG
(Water/Oil/Gas) and not a CHEAP imitation (Red and White) from AWAY :cool:
The problem with old ThruHulls is that they are not SeaCocks. The WEAK
point is the ThruHull stem as it is attached to the hull with a threaded nut.
As the metal corrodes and gets THIN the stems can just twist off or break
with a hard turn or accidental pounding. Thats why you keep a wood plug
tied to each ThruHull. SeaCocks have no pipe stem and are cast flange
connected to your hull. Check out SeaCock Service Manuals and Installation
Bulletins at www.groco.net. Quite an eye opener on ThruHulls :nerd:

Happy Holes in your Boat :egrin: :egrin: