Fuel Coffin and Moving It Forward

[boatnamesue]

1976 170

Hey guys.  I'm beginning to plan the details for what I hope is my soon-to-be half tower installation.  I will not be removing the deck– and it's this that will make it a bit difficult running controls and wiring aft.  I'm planning to reroute all engine control cables, battery cables, fuel line, etc, from the starboard recessed deck panel to under the deck, in between both stringers.  These controls, lines, and wiring will only need to travel a short distance forward before they arise above deck.  This is where my questions come in. 

The preferable area for this below deck access hole for these controls and wiring is just aft to the junction of the fuel hatch and deck.  I would need to move the fuel tank and its coffin forward by about 2-3".  This measurement represents the diameter of hole to be cored for pass through of engine controls.  Those whom are regulars here on this forum most likely recall my fuel tank replacement earlier this year.  I noticed during this replacement that the plastic fuel coffin liner seemed bonded in place, perhaps to 90º angled recessed deck flange.  Not sure.  What I'd like to know is what steps I would take to loosen the bond, or if possible and safe, cut out the bond.  At which point the coffin could be slide forward.

The 1st & 2nd pictures below are of my tank coffin.  The red lines are meant to indicate this "bond" of coffin to whatever it's bonded to.  And I must say, I specifically remember looking at this "rim" area of coffin.  It's seamless, really.

The 3rd picture below is of photo of a '76 170 I found online to help you visualize the fuel coffin area in between the stringers, as well as seeing the amount of forward space.  The area aft of the dotted red line (X's) indicates the 2-3" space needed for the deck access hole.

[mshugg]

If the coffin on your 222 is like the coffin on my 20CCP, it is not a separate piece bonded in.  It is a tub that is molded into the liner, all one piece.  It should still possible to move it, though it may be a lot of work.  Maybe rig some kind of ledge to support it on the inboard side of the stringers?

[Que Pasa]

Sugg is right it's a molded fiberglass liner.

[boatnamesue]

If the coffin on your 222 is like the coffin on my 20CCP, it is not a separate piece bonded in.  It is a tub that is molded into the liner, all one piece.  It should still possible to move it, though it may be a lot of work.  Maybe rig some kind of ledge to support it on the inboard side of the stringers?

My hull is the 170 model, '76.  Not sure if this will make a difference or not with your reply.

[boatnamesue]

Sugg is right it's a molded fiberglass liner.

The liner or tub, whichever term is correct, is definitely not made from fiberglass.  It's a poly plastic of some sort.

[mshugg]

It’s expensive to set up the molds for Pollyethelyne.  I doubt it was used in 1976.  You can’t bond Polly to anything.not even 5200 sticks reliably to it.  What makes you think it’s not glass?

[boatnamesue]

It’s expensive to set up the molds for Pollyethelyne.  I doubt it was used in 1976.  You can’t bond Polly to anything.not even 5200 sticks reliably to it.  What makes you think it’s not glass?

It did not have the same stiff-like characteristics as fiberglass.  And it incredibly thin, thinner than any glass built box I've known.  When prepping the coffin for the new tank, I drilled 2 thru holes to allow water to escape.  It was millimeters in thickness.  You are spot on with your statement on bonding poly.  Perhaps it is possible to mold a coffin with only a layer or two of cloth. 

[RickK]

Maybe your boat was made with a Friday pm liner? Anything is possible.

[mshugg]

Most likely reenforced with chopped strand.  In those days it was either that or woven roving.  My console and below deck boxes had some roving, but there were areas that just had chopped strand.  I’m not sure if the chopped strand was hand laid mat or chopper gun, but based on the inconsistent thickness, I’m guesssing chopper gun.

[Que Pasa]

It’s expensive to set up the molds for Pollyethelyne.  I doubt it was used in 1976.  You can’t bond Polly to anything.not even 5200 sticks reliably to it.  What makes you think it’s not glass?

It did not have the same stiff-like characteristics as fiberglass.  And it incredibly thin, thinner than any glass built box I've known.  When prepping the coffin for the new tank, I drilled 2 thru holes to allow water to escape.  It was millimeters in thickness.  You are spot on with your statement on bonding poly.  Perhaps it is possible to mold a coffin with only a layer or two of cloth. 

I thought you were sure it isn't fiberglass. My tub was the same way, it's fiberglass.

[boatnamesue]

   
I thought you were sure it isn't fiberglass. My tub was the same way, it's fiberglass.

It did not have the same stiff-like characteristics as fiberglass.  And it incredibly thin, thinner than any glass built box I've known.

[Corynelsonflkeys]

Sorry to stray away from the main topic.. Do you have any drawn up plans or ideas on that half tower yet? I'm just curious because mine originally had one when I purchased it and I took it out a few times before starting a full restoration and it was quite frightening(it was blowing 25-30 though). The standing location of mine was a couple inches higher then the top of the gunnels. I had only 10gals of fuel in the boat and a 150hp evinrude on the transom so that might have been the reason it was frightening.