First let me say that I have searched both on Google and also on here without much luck…so here goes a very basic question…
Are the fin placements on a twin different than the front two fins on a quad AND different than the side fins on the thurster? If so, which twin fins would be better in a thruster and on a quad? I i have seen some twin fins that are made with the tabs further up so that that the fin is positioned further back. Like in the photo below. Thank you!
Well, are we talking twin keel fish or a 1980’s twin-fin? Your title seems to imply we’re talking a keeled fish, but the body of your question pushes more toward a regular twin-fin. These are different boards. So, fish keels are typically set back toward the corners of the board. Whereas classic twin-fin (e.g. Mark Richards twin-fins) have the fins set just about where the front fins go on either a classic quad or thruster set up.
The fin offset you illustrate is good for using in the front slots for a thruster or quad and running as a twin-fin.
HP Thruster and quads seem to have the trailing edge of their rail fins at around 11 inches.
I think, and will be corrected if I am wrong, but an MR style Twinny has the rears at 9.5 or 10 inches. I think the MR twins uses less cant and tow in but am unsure of that. I know Greg griffen is putting twins on his HP twin fins at 8 inches and gets a lot of good feedback from them, even though they ‘look’ to be too far back
Moving the tabs forward on teh fin a lot, can have the trailing edge of the fins very close to rail edge, and with a good amount cant be dangerous to the rider going from sitting to prone.
I’ve lost a center fin on a bottom turn once and kept surfing, the rail fins were kind of oversized but were way too loose and squirrelly in the thruster position. Was kind of like driving on ice.
I’ve recently moved my high aspect ratio rail fin tabs forward to have my fins further back, and much prefer it.
Great idea - moving tab positions to adjust fin placement. With a dual plane laminating surface you can also build your fins with ‘tilted’ tabs to adjust cant or with some additional tweaks, adjust toe-in.
This a keel fin Greg Griffin made for my brother’s Firewire fish. Notice how big it is and where the tabs are. I have it next to a double foiled keel I made.
Pretty sure he is not.
Although he probably changes the placements for different length boards, his are significantly further back than 8".
Yep, my bad. Sorry.
For the record, I’m no pro. You don’t mention board length, which would affect placements. However, just for fun, let’s suppose a board length of 6’0". Following would be the very rough numbers as I’ve gathered over the years:
Thruster/quad fronts would be around 11" - 11.25", with ~1’4" of tow on a 4.5" base
An 80’s style twinnie would be somewhere around 10", with 1/8" - 1/4" tow on a 5" base.
A twinzer main would be somwhere around 8" - 8.75", ~1/8"(?) tow on 5" - 5 1/4" base.
A Griffin twinnie will be in the 6" - 7" range and is it’s own animal
A traditional keel fish would generally be around 5.5" - 6.5", with zero to 1/8" tow on a ~8" base.
If you are creative with your fin plug placement and up for making fins with modified tabs, you can combine some of these options into one board. Just recognize that there will be compromises to be made.
I’ll just add that the sample fins in the pic you included are actually small quad trailers with a base length of around 3 3/8". That’s why the tabs protrude past the leading edge of the fin.
Laters. Nice to have sways back online again.
