Intergral tanks (diesel, water) in aluminum yacht?

Dear all,

I have now launched an extensive project, to refit a 50ft aluminium ketch (constructed and build by Bob Derecktor in 1998). I aim to convert this capable off-shore racing yacht to a even more capable blue water cruiser, suitable for singlehanded sailing. There will be NUMEROUS technical and design challenges along the way, so I will likely be posting questions here regularly. Please find attached below a picture of the hull today (with new deckhouse and cockpit, done by previous owner), as well as a picture under sail from early 2000 (she's been on the hard since like 2004).

Today's question:

The interior was completely stripped, sandblasted and then painted with epoxy primer. There is no real "bilge" (rather a flat bottom), but a very sturdy framed structure (see picture). I am trying to figure out how to best use this volume. To just cover it and leave as is seems somewhat a waste.

Would this area be suited for integral tanks? The structure is baffled enough, it seems.

Any pro's and con's?

And yes, I obviously need to make sure the epoxy primer can withstand diesel (or replace or repaint, first).

 

Welcome to the Forum Claes.
It should be possible to convert most of this space in the bilge to tankage - and by so doing you would create a 'double bottom' like what ships have.
It would be worthwhile though to do a fairly detailed weight estimate before you start - not only the weights of the fuel and water in the bilge, but all the outfit items required to convert the vessel into a blue water cruiser.
Will she still sail well if she is a few tonnes heavier?

 

Well, that is a reasonable and great question. I am mindful of weight overall, and I will take some steps to keep it down (will aim for electrical engine instead of diesel; will have watermaker instead of large tanks; etc). I have not done any calculations, however, so I do not really know where the practical weight limit is....

 

Have you got a body lines plan of the boat?. You will need it. You will need also to know the actual boat weigth and CoG.

 

Yes, I do have the drawings, and a pretty good view of the weight. I do not have the CoG, but I have a marine engineer available who will assist with necessary calculations.....

 

Perfect, that will allow you to solve most of the problems. He may have to perform an inclining test to find out the CoG.