OK, I read the original post again. The new tank was made to be an exact match to the old. Did you check that it is a match?
The old tank has worked since the start of time ( well at least 1984).
Why would you change the orientation now??
It's sort of ' if it ain't broke, don't fix it'.
If I understand your concern, it is that the top of the tank is not parallel to the deck. Am I correct?
Who says it is supposed to be level with that surface?
Finally, I respectively disagree with your tank builder advice.
Read this article
The old tank has worked since the start of time ( well at least 1984).
Why would you change the orientation now??
It's sort of ' if it ain't broke, don't fix it'.
If I understand your concern, it is that the top of the tank is not parallel to the deck. Am I correct?
Who says it is supposed to be level with that surface?
Finally, I respectively disagree with your tank builder advice.
Read this article
How to Install an Aluminum Fuel Tank on Boat or Yacht - by David Pascoe
Many people blame aluminum as being a bad material for fuel tanks. Actually, it's not. All materials have their strengths and weaknesses, and the problems with aluminum tanks are problems of proper installation, not the material itself. Properly installed, aluminum tanks will usually outlast the...
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