Fuel Tank Location and Stability

[joliette]

My twin integral tanks are constructed from grp over ply. They are over 40 years old and no longer suitable for use, due to the ethanol that is now going into our petrol. They are located down the port and starboard sides beneath the cockpit floor. It is very difficult to access all areas of the inside of the tanks to prepare them for application of a protective coating and, in any case, it is a risk that such a coating would fail. Removing the tanks or removing the tops to prepare them for liners would require major destruction of the cockpit, which is something I would like to avoid!

I am considering leaving the existing structure in place and inserting two new tanks, between the old tanks, down the centre line of the boat. This would shift the weight of the fuel lower in the boat and about the centre line, which in my mind ought to increase stability(?)

The boat is a 25ft Settimo Velo a deep V Levi design, similar to a Triana.

Can you see any issues with what I am suggesting or think of any alternatives?

 

[burgundyben]

Sounds ok to me. You need to make sure the structure supporting the tanks is good, its a lot of weight when crashing about in rough weather.

 

[oldsaltoz]

My twin integral tanks are constructed from grp over ply. They are over 40 years old and no longer suitable for use, due to the ethanol that is now going into our petrol. They are located down the port and starboard sides beneath the cockpit floor. It is very difficult to access all areas of the inside of the tanks to prepare them for application of a protective coating and, in any case, it is a risk that such a coating would fail. Removing the tanks or removing the tops to prepare them for liners would require major destruction of the cockpit, which is something I would like to avoid!

I am considering leaving the existing structure in place and inserting two new tanks, between the old tanks, down the centre line of the boat. This would shift the weight of the fuel lower in the boat and about the centre line, which in my mind ought to increase stability(?)

The boat is a 25ft Settimo Velo a deep V Levi design, similar to a Triana.

Can you see any issues with what I am suggesting or think of any alternatives?

Have you looked into creating a couple of access hatches into each tank area and installing flexible fuel tanks?

They can be made to any size and shape and include built in baffles, the two access points (one at each end) would provide enough access to reconnect them and place them correctly.

 

[joliette]

I've looked at the Nauta flexible tanks. These are all standard sizes in a pillow type shape and you can't fit fuel sensors. I haven't been able to find a firm that does custom liners. Can anyone point me in the direction of such a company?

It's possible that a custom liner could work, but I'd have to spend a lot of time working on the interior of the tanks to remove the central baffle and all of the sharp grp edges from around the underside of the existing lid.