I don’t think there’s much downside. Your vee panel will limit flex in the tail anyway, which negates the problem of locking down 10’5" of tail with a rigid box. Your vee will also keep the tail thick enough that you can place the box as far back as you want.
The main reasons for going glasson on a longer board or a single fin are to let the tail flex (better noseriding hold) or to move the fin farther back than the tail thickness would allow a box to be placed. So you’re covered.
Other considerations like weight (couple oz?) & drag (if any) & extra steps to build sound pretty meaningless in the board you’re planning. Go for it - versatility is a good thing.
I made a spin on a retro fish last summer that has a round tail with wings instead of the butt crack. I also used the lock box quad fins - I went for the Pavel speed dialers and it’s a great board - I took it to Australia for a month in the summer and surfed it up to head and a half high. I found it really responsive and it slides less than the traditional twin keels. I have also put in a 10’ 1/2" box in and I used the board with the quads plus a small centre fin and with a single larger centre fin. Due to the type of board and the weight of cloth I glassed with it turned out quite heavy but I dont realy think it was a dissadvantage - it suited me fine through a range of conditions - also surfed it on my local reef at home in Porthleven England which is a pretty sucky wave and again it holds in fine.
I saw a nice modern fish this week that a freind was riding and he used FCS - using small side fins from a longboard in the rear - that also worked out well.
Good luck and dont wory about the weight - often works to your advantage if youre like me and not too good at generating my own speed - a weightier board kind of helps you do it by itself.
I’m thinking about doing an egg for myself soon - maybe with a quad set-up - just made a single fin for a friend that you can see posted this week.
This is a full style egg (7’10") out of 2.5 lb EPS with double 6oz S cloth single 6 bottom.
It was not the wieght that bugs me (I sometimes like a little, espically on boards like this) its having this big open 10.5 box open in a critial water
flow area. I think the ‘subte’ bottom is going to allow me to have the most verstility.
I’m most certaily going to make a little balsa insert for the box with a layer of 2oz around it.
I’ve not really worried too much about it but I guess I should try flushing the box too and see if it makes any difference - should be easy enough to make a blank that has a pin and screw just like a fin - lightly glassed balsa sounds a good idea but maybe just a chunk of more resitant foam may work too.
I’ll get my pictures in order and post a few of my recent projects.
