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fretz

questions surrounding a new tank

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Here in NJ our season is over a little early. Normally we would be in till november but this year the original tank in our 84 2020 gave us so much trouble we cut our losses and went with portable tanks. The fittings on the tank are so corroded that we cant open it up to inspect or clean the tank.

 

the plan is to pull it out and replace it which is easy enough. My question is what to do about the foam while i'm in there?

 

If i dig it all out do i have to replace it? id consider glassing in a reinforcement before replacing foam.

 

Can someone confirm that the tank is foamed into a coffin type box? If it is can i just cut the box out to access the bilge?

 

If im cutting i would probably cut the floor to the transom to address the indeck fish box. i sealed it shut a few years back but does anyone have a way to make gutters and drains for that box?

 

We love the boat but it is very heavy. When installing a new bowlight i was amazed at the water in the foam directly under the deck. I want to address the issue as best i can without removing the cap from the hull.

 

Thanks for the help and ill update with some photos when we open her up.

 

Fretz

LBI NJ

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Making the gutters is easy. Take a piece of 1" pvc pipe (or whatever size gutter you want), and rip it in half. Take a 4x8 sheet of white tileboard from any hardware store and rip 2 12" pieces 8 ft long. Cut one piece 3 ft long and butt up to the 8 ft pc so you now have an 11 ft lenght. Next, hot glue the 10ft lenght of pvc pipe to the center of the tileboard. Mix up some bondo and make a radiusd filet where the pipe meets the tileboard, then sand smooth. Now you have a mold to lay up your gutters. Be sure to make a 2" flange on either side when making the gutters so you have something to attach to the existing floor.

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Tanks out!

 

It took us about 5 hours to remove the console, floor and then dig the foam out. I was expecting this to be alot harder than it was. The top of the tank had several holes big enough to put a pencil through. Most of the damage was isolated to the box built around the tank connections.

 

Were pricing a new metal tank and i want to mount it in saddles made from plastic wood instead of refoaming the tank. All the plastic tanks involved a compromise

 

Looking at the coffin box id like to put a drainage hole in the bottom then open up the floor behind the tank and install a bilge pump. Theres no way im digging all the foam but a void that allows the foam to drain should help the situation.

 

Thoughts???

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Edited by fretz

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My coffin has a drain into the rear bilge area where the bilge pump is. ( where you have sealed the hatch. )

My 1820 never had foam around the tank.

I hope it lasts a long time, not sitting in wet foam.

Are you going to try to replace the fuel fill & vent hoses?

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Were replacing everything related to the fuel system.

 

If I make frames to support the tank instead of the foam how many should I use over a 60" length?

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Was the only location of the holes right there at the fuel sender?

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I wonder if the pick up / sending unit area of aluminium wasn't marine grade?

Or an electrolosis issue?

 

Not sure on tank support spacing. 25% of length locations?

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That would be ends, & every 15".

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all the holes were within the box used to keep the foam away from the tank connections.

 

there was always standing water on top of the tank. we tried sponging it out but the boat sat during the week and there it was.

 

electrolysis is something i never thought of but the tank was grounded and there were wires for the sending unit in the water.

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8 years later...

Water is getting into the coffin again.  When we sealed it i used foam backing rod and a marine sealant.  I know it wasn't 5200.  

At this time I'm assuming that the sealant has failed as the water isn't salty.  There are a few places where it appears to have separated.

Add it to the winter list!

I've done a bunch of glass work to the floors and glassing over this hatch joint is not out of the question before rolling on new non skid.  Thoughts?  What sealant would last longer if i go that route?

The coffin cover could be re-cored if necessary while I'm at it and I still have those pedestal seat bases which are in the way for a leaning post with a cooler which we need.  Have to look on the bright side!

Fretz

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5200 is permanent and almost impossible to cut and remove. 4200 would be more suitable

Glassing takes away tank access..

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If you replace the old sealant, 3M 4000UV or 4200 would  be a good replacement.  Be sure to clean anywhere the sealant will be applied so there is no contamination from the old sealant.  Consider running a piece of 40 or 50 lb test mono at the bottom of the area the sealant will be applied so if you have to remove the lid in the future, dig the mono out and pull on it to cut the sealant for quick removal.  

Is the tank coated with coal tar epoxy?  If so, then you can think about glassing the coffin lid into place.  If you do this, after the glass work is done, make about a 2" border where the original joint is centered in the border, then apply your non-skid on either side of this and leave this smooth.  This will break the monotony of one large area, indicate where any future cut line should be if you need to access the tank, and provide an area to re-glass the lid without disrupting the surrounding non-skid surface. 

Prior to glassing the lid in or re-installing like the factory did it, I would run a flexible hose from the lowest point of the coffin box back to the inspection port over the fuel sender unit so you have a way to pump any water out if it gets in there again.

Thoroughly inspect the access hatch over the fuel sender to be sure it is good shape and not the source of your leak.  The o ring gasket sometimes gets dislodged and does not seal against the screw in lid properly.  Also look at the base and be sure it is properly sealed to the coffin lid.

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Since you mentioned  3M 5200,  I'll post this again, since my Original Posting from earlier in the year , was lost when the site went down....

There is now, a product that will Remove  5200 , and it's pretty easy to use.  I did a test with it, an was pleasantly surprised how easy it worked.

Here's the site where you can get it and some information about it.       

https://store.marinebeam.com/un-hesive-3m-5200-sealant-and-adhesive-remover/

 

Don     "The Dr. Ann  R-236

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