How do the old 15a type outboards get over 50 mph?

[Chad Morgan]

I’m not seeing a fin at all on the De Silva comet yamato tunnel plan. I have been looking at the plan for hrs and still trying to figure out how to read it as its not a full size plan. It uses some sort of base lines and I think it may be expected that the builder knows what he’s doing but i’m a noob having only made 1 boat and that was off full size plans. One note on the plan just says “typical frame construction” and theres only one picture of a bulkhead but i can see theres 5 needed but they wouldnt all be the same size surely.... Plan is marked 1993 so It’s an old one. I will keep researching and try to get a better understanding of how to use the plan better.

I still have a couple more plans on the way from Nyberg, the “Jack Rabbit” and his “whippet”.
They might be a bit more newer and I think they have a fin.

I havn’t seen any one talk about the yamato comet De Silva tunnel plans so not sure if there is many around or not.

[Chad Morgan]

I can see a couple of things on sponsons that would help get grip in turns and he’s got a note and squiggly lines saying something about vacuum underneath at the back. but no fin that I can see.