Joey,
The tunnel boats that I build and race are of my own design. Construction is wood over foam. The cowling is a Dumas cowling however I find them too low at the rear so I added material and changed the height and profile a little bit.
This is a 7.5 tunnel that is similar to my very successful (to me) previous design with only the mid section revised. The previous design is what you see in the posting picture with the purple cowl and natural sponsons. We'll see if it's a good idea or not when it hits the water this spring. I'm pretty confident in it so my initial thought is to give it the Nova Rossi 7.5 OB for power.
The next boat is for development. I wanted to be able to remove the sponsons so I can try out different designs without having to build an entire boat each time. Nothing new about the concept of removable sponsons. It's just something up till now I never had built.
I have one set of sponsons of my latest design, same as the purple boat. I'll use these as a baseline. The sponsons on the development boat are of a new design that I'm trying after spending some time with Rod discussing sponson theories on the water side and then I just removed as much mass as I could on the top side and width.
I'm also considering an electric tunnel but I need to learn more about that class first.
Hope this helps.
Duke,
I look forward to seeing you out there as well.