Building a Sea Chest

[mbmcdermott18]

Well I had my first set back this afternoon. Tried to make the lid for the box myself out of some 1/2" acrylic that has been in the garage for a while. Couldn't get it right. The cuts and the radius were both jacked up. I am going to go by the glass shop tomorrow morning and get them to make one for me. Thinking I may get two just to carry one on the boat in the event the lid ever cracked it wouldn't cut a trip short.

Ordered some 316ss machine screws to hold the pumps and the lid down. I ended up tapping the floor of the box and will hold the pumps down in there with 316 8/32 screws.

For the lid I am going to tap the flange and run 1" 10/24 screws it. I am thinking I will use around 24 screws in the top. 8 on top and bottom and four on each side. I am going to draw it out in the morning.

I tapped a piece of the flange (the flange is solid laminate aprox 3/8") that I trimmed off and tapped it and ran a screw through it. then I put the piece on the floor and put a foot on either side of the screw and tried to pull it out with a pair of channel locks. I couldn't pull it out even after putting about a 1" bow in the 18" piece so I think it will be fine with that many screws in it. I am planning on putting some silicone or something to keep them from vibrating loose. Maybe loc tight? Any comments or suggestions?

I need to order some sheet gasket to cut my gasket. I was thinking of using 1/8 or 1/16 epdm rubber. There are several options and I don't know much about the different choices. The two that I recognized were silicone and epdm. Any suggestions on these types of materials?

[mbmcdermott18]

Nothing major going on in the last couple days just made a couple pieces to epoxy to the box that will screw to the hull to hold it in place. Also removed the rest of the pumps from the bilge and spent the day sanding the bilge yesterday. Got most of it knocked out.

Regrettably I will be out of town this weekend and unable to work on the boat. Will be back on Sunday and try to finish up the sanding and get a few holes filled with thickened epoxy. I am going to law down some awlgrip snow white in the bilge before I install the chest. I would like to get everything prepped so I can paint next weekend. We will see how it goes.

[mbmcdermott18]

The chest and bilge are painted and I have the chest partially assembled. I hope to put everything back in the bilge and install the sea chest this weekend.

I am wondering what to use for sealing the many threaded connections when plumbing the chest. In two areas I have to orient the fittings a certain way so they may not be dogged down as tight as possible. I am looking for a compound that will be strong enough to keep a tight seal.

I have asked a few folks and got different opinions from pipe dope teflon tape marine sealant etc. I was thinking of using 4200 so it would be strong enough to hold everything together but I would still have the ability to disassemble everything if need be.

Any ideas on what would be the best product for this application?

I will post a few pictures this weekend. I have been bad about remembering to take pictures as I go along.

[strick]

If it involves keeping your boat a float then I would use 4200 or 5200. Air mar recommends using 5200 to seal their threaded thru hull transducers.

strick

[Caymanboy]

5200.

[mbmcdermott18]

Here is a picture of the sea chest assembled I will take some more detailed pictures tommorow as I install.

[Caymanboy]

I'm confused, (which would not be the first time!).
A sea chest to me, is a single inlet in the hull (bottom) with one valve, which then either has a box or pipe, which then in turn has seacocks and hoses going from it to the various compents you wish to supply, IE:, A/C intake, generators, main engines, washdown pumps, etc. That way in the event of a catastrophic failure, you close one valve. It also gives you the ability to have only one sea strainer.
The picture I see, is a sump tank.
What are your intentions for what is in the picture?

[Caymanboy]

Sorry, went back to the first post.
My concern would be the supplys you have, appears they are either 3/4" or 1"? That would be a total of 1 1/2" or 2", is that enough to supply ALL three of those pumps when they are running? They are what, 1500-2000 GPH apiece?
The next thing to figure out is, what kind of p/u's do you have? If there is no scoop on them, the water will get pulled out of the box, if there is, water will be pushed into the box, all the time.