[MHml] Stern shape

[Allied]

> Hi Colin, I have been following this thread in some confusion
> What you are doing to your boat could have extensive consequences, but I 
> can
> not work out quite what it is that you are doing. If you could produce a
> sketch or a photo it would allow some of us who have design background to
> give useful advice based on what you are actually doing as opposed to what
> we might guess based on the descriptions so far.
> Cheers,
> Peter
Hi Peter,
it would be easiest if I did a picture, but I have never got round to 
setting up a place to put them, for others to view. So I will do my best 
with words.
The boat is loosely built about a stretched Frank Pelin 32 foot Cat design. 
It was built to 40 foot, with all dimensions scaled up, using 3/8"ply on the 
hulls and 5/16"on the decks, by an Englishman, working in NZ, about 20 years 
ago. He built it very light weight and I believe it was a very fast boat at 
that time.
The next owner put in another 400 mm of height in the main saloon. The next 
owner put in a shower and toilet. Then I came along and took off the very 
heavy timber rudder system and replaced it with a light weight SS pipe one. 
That was the good bit, but I added an inboard Diesel, hydraulic drives, 
fridge, freezer, house batteries, wine cellar (get my gist). By this time 
the original water line is about 5" lower aft, than built and the bows are 
out of the water. The hulls are quite sleek, with maximum draft and width 
about 2/3's back at the centreboard position.
What I have done with these alterations, is to make a tapered extension 
keel, about 40 mm wide and glued it on the outside of the existing keel, 
starting about 2 meters forward of the old transom out to 700 mm aft. This 
changes the upturn aft, along the length of this new addition, from what was 
about 180 mm, to 50 mm. I have then glued on foam, and made moulds and 
poured two part foam, around this area, taking out most of the taper towards 
the old transom (about 70 mm each side at the widest) and making the bottom 
'V' go from about 15 º / side at the start of my added buoyancy, to almost 
flat, at the old transom. Just by sight, I decided that a nice curve at the 
back would look right and having no experience/knowledge, that is how I 
shaped it. Then a friend who is going to do the glass over the foam for me 
came along and said, that I was wrong to have that shape and a flat back was 
the way to go. So now I am asking for advice.
I am not going to do any final finishing this year, just make it sea worthy 
and see what my additions do, to how the boat sits and sails. Hopefully I 
can then do alterations/improvements next time it is out and do final 
trimming and painting then. But all input is very much appreciated, as I am 
not a designer, I just do what looks to be right.

Colin