Transom Bilge Pump Drain Hole Location

[ThumbsUp]

Hello fellow Cbrats,

Well, i just drilled a hole through the side of my boat for the transom bilge drain hold fitting (3/4") and I hope I didn't drill to low. My intention was to drill it low to minimize back flow and match the live well drain on the port side of the boat. Now I am really nervous Is it time to call my fiberglass guy or do you think I am ok?

Nervous in Nevada.....

I am not sure how to post a pic in the forum so I will post it to my album

[Sunbeam]

Actually, you don't necessarily want the hole right up high at the gunwale. It's nice to have a loop that rises up on the inside to keep nuisance spray out and to keep as much "backwash" as you can draining out. On many 22's the fuel vents were right up at the gunwale and that made for water issues as spray was driven in/down

On the other hand, if the hole is too low it could potentially cause a siphon.

I'll go see if I can find the photo in your album and post it here.

Okay, here it is:



So, I would probably not have put it that low, ideally (I think mine is up one strake), but it may still be fine. Definitely put a loop in the hose that rises up to right under the deck before turning back down toward the bilge.

One difference with the live well in the port lazarette is that that goes up, but doesn't go back down (no siphon potential).

Let's see what others have to say.

[thataway]

That should be fine. It is at about the same level as my main bilge pump amidships. Never had any back siphoning. You are almost a foot above the static waterline.

[Rob & Karen]

That is about the same level as mine which were factory installed. See the attached picture.

http://www.c-brats.com/modules.php?set_albumName=album686&id=IMG_1361_2&op=modload&name=gallery&file=index&include=view_photo.php

[ThumbsUp]

Thank you Sunbeam and Thataway, I've been kicking myself all day for not posting this question BEFORE DRILLING. But, as always, you are both so helpful and have given me re-assurance that the location should be fine. The midship bilge drain on my boat is the same as Thataway's. About the same height as my new drain line.

I would have never thought to install a loop in the drain line up to the deck and down to the bilge, makes perfectly good sense. Thank you for that suggestion.

Corrugated flexible tubbing vs smooth tubbing for the bilge line? Does this make a big difference? I've read somewhere that smooth tubing increases your gph flow rate. I am installing a Rule 500 gph bilge for a raw water wash down/backup bilge.

My next project is the raw water wash down. I am going to start searching through the forums for info.

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Thank you Rob and Karen. The two holes below the port Lazarette (hope I got that right) is what you are referring to? One hole for the live bait well and the other for the bilge?

Ok, starting to feel a little better now. Thank you Cbrats Such a great community.

[Avidmagnum12]

Should be fine but.......

One time on my 22 when it was loaded heavy. Four dive tanks, big cooler, 2 BCDs with lead and water in the back of the boat from rinsing the gear. You get the idea. I ran the rear bilge and pumped out the water. Went in the cabin for a time to cool off with the AC. When I came out you can't imagine my shock when I saw the cockpit filling with water! Turned on the manual bilge pump and the water went down. Turned it off and I could hear water coming back in. Closed the thru hull for the wash down. Water still coming back in..WHAT did I do. Getting dark now. Figured the best thing to do was get the boat on the trailer for the night. Could not find any reason for water intrusion. Next day put boat back in the water....Everything was fine....till I rinsed the gear again.....more water!

Then it hit me....with the boat so stern heavy the bilge exit was in the water and siphoning the water into the boat. Out2C had a flexible line over the transom. Raised it a little and all fixed. Felt kind of stupid. Had the boat for four years and never had a problem but never had as much weight in the back......just saying......things happen! Tom

[thataway]

That should be fine. It is at about the same level as my main bilge pump amidships. Never had any back siphoning. You are almost a foot above the static waterline.

[ThumbsUp]

Thank you Bob.

Should I use 3M 5200 to seal the bilge exit fitting or marine silicon? I worry about using the 5200 because it's permanent and I wouldn't be able to remove the fitting if there was ever a problem.

[rogerbum]

[Sunbeam]

I like to use butyl. It's very sticky and seals well, and lasts for decades (stays pliable). It does not have adhesive properties, but then most through hulls that I have seen are attached and held on by threaded rings on the inside, so no adhesion is needed as they are held on mechanically. When it does come time to change, repair, or re-bed, it is easily removed with mineral spirits. (However it's not good for fuel fills.)

I would never ever use silicone. Why? It doesn't seal all that well, and when the time comes to re-bed you will be cursing and hating it forever (which is how long the residue lasts that prevents anything from ever adhering again).

Quite a few things on my boat were done with silicone. Others were done with polysulfide. The silicone ones were long, horrible wrestles to deal with (that's putting it mildly); the others simply required a cleaning with mineral spirits, and then I had my choice of how to re-do them. Ahhhh. Like night and day.

If you need adhesion, then a polyurethane such as 5200 with immense adhesive qualities can be a good way to go. For a bit less adhesion, 4200 or other brand. These can yellow in UV light, and are a bit tough to remove (but not toxic tough, like silicone). I find that most of my bedding is just bedding, and doesn't need the super strong adhesion -- so the bedding is there to keep water out, which butyl does well.

3M 4000 is a "newer" caulk (polyether) that has some adhesion and UV non-yellowing, but I haven't been using it long enough to know for sure.

Polysuflide is a bit hard to find these days, and has a shorter shelf life.

Anyway, as you can tell there are many ways to go, and many opinions. I would absolutely say no silicone, and beyond that, would tend to use butyl when there is already mechanical fastening.

[ThumbsUp]

I've used Silicon for several boat projects and its a real bear to clean up. Not to mention that after a year of being in the sun, the silicon turns yellow. I just ordered DAP Butyl from Amazon and will start using that instead.

What cleaning solution would you recommend using to remove silicon? Mineral spirits or acetone?

[Sunbeam]

[thataway]

There are many different types of silicone bedding compound/adhesives. For example I put new Lexan Windows when we rebuilt the Cal. 46. I got a GE product recommended by window glaziers for lexan. It was hard to work with--the lexan had to be set off the fiberglass by 1/8" cork/rubber pads, and lots of masking inside and out. It looked fine--but the first time I took the boat out in salt water, and spray got on the windows, the sealant began to leak. I called GE products--and they informed me that that silicone was contraindicated for salt water! I found a fellow who was doing super yachts, and he put me onto a Dow silicone--same characteristics, but this was resistant to salt water. I got a dabble on one of the stays, and 8 years later it was still there! But the windows never leaked!

Napa or Mineral sipriits (real, not the Calif "fake" mineral spirits) are best for cleanup. Also a plastic "knife or spatchula.

[ThumbsUp]

Thank you Sunbeam and Thataway. Just ordered Butyl tape from the sitelink provided and that amount should last several years!