Exactly.
That was a lot of diggin’ for one word.
The main reason that single foils have become so prominent , is because they are far easier to design , foil, sand, finish coat and polish …so, more cost effective to produce…IMO… !!
Don’t know if I completely agree, but it is kind of the same argument for and against Channels. Maybe an Industry dictate. One thing I know is that if you bring something out of the norm into a Glass Shop; They will charge you more for the extra fin or fins, Wings, Channels etc. but honestly the average glass shop that wants the business usually doesn’t charge enough to cover it. The result is a strict attitude af charging for every little extra or not charging enough if anything at all.
When I make a glass on single fin , I make them 12mm to 15mm thick …always works for me . The standard slide boxes on the market predetermine your fin thickness at 9.8 mm (?)…too thin for me . I wanna make my own boxes at maybe 15mm thick - the fin just seems to foil nicer at that thickness (and work better)…I reckon twinnies feel better with double foils too…maybe I’m dreamin
Nope you’re not dreaming. That’s the way they were done in the early origins of the Twin Fin. Double foiled must work because guys are still doing them om Twins.
^ completely correct, imo. I only have broader experience w one master fin maker, so small sample size, but i doubt any others would say flat on one side is apt to be on the absolute best possible fronts in any fairly conventional (e.g. Merrick, F4, PC series, etc) tri/quad set unless that’s all they’re offering for sale, and that is (probably?) the most likely place for flat sided to compete well w all other possible foils
Hopefully I won’t bum Rich out by sharing this, but I have a set of custom quad rears he made me that are indispensable in the fin quiver. They’re 70/30, and for smaller waves and larger waves you reverse the placement, so that the 70 is on the outside or inside depending on whether more engagement and drive is desired/beneficial.
Unless the fin cant is supposed to be 0 degrees, that is of course really only practical for FCS or a box type with the cant in the box.
Ive always thought that the early 70’s twin fins ( pre-MR) were great performers in a wide range of conditions . They left a void when they were dropped , which has resulted in the popularity of the Fish designs…which are basically just a 70’s twin , with a fish shaped tail.
nah,not even close RDM…early 70’s…I had one with a tail that was aprox 16"/17" wide , with a transom on the tail…heaps of thickness under the back foot.
Just a little food for thought…
From the mckee website "Mckee’s ‘Width between back fins’ formula, is calculated to give the most fluid and redirectional interchange between turns while maintaining drive, eliminating tracking, rail grab and the need for baby back fins, all associated with having fins too close to the rail. In the past l have placed fins in hundreds of different positions all over the tail. For the ‘M4Quattro’ purist, the ‘Mckee M5 Multisystem’ is just a security blanket or like training wheels because for them the ‘Thruster’s’ central fin is obsolete. The quad cluster can be moved forward to loosen up a board and for shapers of custom boards, many compensations can be made for weaker riders or for special needs such as looser guns but with the advantage of not losing drive. Although taken off the current formula there is the shapers option to move the cluster at any amount not exceeding the stupidity level. I personally had great results on pintails by moving the positions forward up to 2cm or ¾” forward. The videos of Tom Carroll in Hawaii are examples of the result of these positions — The variations are limitless!
Stiff side fins give drive if on front.When on back can provide drive but less predictable hold depending on flex
Central or fully-foiled tail fins provide less drive than flat-faced side fins but allow easier & more fluid turn initiation
Bigger front fins than back fins provide a more pivotal feel: Bigger back fins than front a more directional feel
From Robin Mair’s Hanalei Fins website: “Many of the fin designs feature hollow inside foils for an extra performance boost.”
from Rusty Preisendorfer’s on Surfline: "Early on I took a fairly simplistic approach to it.
Early quads were an attempt to add drive and control to twins. In 1980/81, Twins were de rigueur. Since 1982/83, tri-fins were most surfers’ experiential basis. In my mind, I’m starting with a tri-fin. So I took the rear fin on a tri, and was theoretically splitting it in half. The more the rider wants the feel of a tri, the further back and closer together I’d keep the fins. If a rider was after more of a twin-fin feel, I’d move the rears towards the rail and the front fins.
My common middle ground: for argument’s sake, a 6’2" tri-fin has fronts at 11" and rears at 3 1/4". A lot of designers go half the distance on a quad, so that would put the rears at 5 1/2" and the same distance from the rail, about 1 1/8". In my humble opinion, I feel this is a little on the neutral side. I split the difference on distance from the tail (tri vs. quad: 2 1/4"), which would be 3 1/4" plus 1 1/8"…or 4 3/8". Easier math: 7’ board. Fins at 12" and 4" on a tri. Half the distance is 6". Split the difference, 5" for a quad. On average, I try to keep my rears about 2" in from the rail. That’s a generalization. It becomes a more complicated depending on tail width and board length.
Fin size: Fronts are similar to tri-fins, perhaps slightly smaller. Rears: profiles similar to fronts reduced approximately 10% in overall area. You can adjust drive by swapping out rears with different aspect ratios. More upright fins for tighter arcs. More rake to add length and draw to turns.
Foils: Your preference on fronts…your favorite tri fin fronts are a good starting point. If you are a fan of cambered fins – stay with them. If you prefer flat-sided fronts, you will probably like them in the trailers as well. Smaller, weaker surf; flats are probably the go as they react a little quicker and provide instant feedback. Bigger, more powerful surf – most prefer cambered or dual (full) foil trailers. Less prone to cavitate and let go. Some prefer full-foil trailers in everyday surf, citing more “feel”…smoother, cleaner, etc. Not as fast.
Cant on rears: Typically, I halve the angle of the fronts. It can vary according to intended use. Smaller softer surf; a little more cant will add some lift and looseness. Conversely, less tilt will increase speed, hold, and drive.
Nose vector (line towards nose): I typically point all four fins to approximately the same place, which depends on board length and type of surf the board is intended for."
That’s right and I agree their demise left a gap. I rode a 5’8 Twin with a wide tail and a very nice 60/40 rail . The rail on this board taught me a lot about what I appreciate so much about a well shaped board. The rail was ahead of it’s time - 1970. It was shaped by a San Diego shaper Ron Cunningham who went on to other things in life. Had a lot of fun on that board. Had it shaped so I could hitch hike with it. Requirement was that it had to fit in the back seat of a VW. Took that board up to the Central Coast of Calif and blew a few minds. Everybody up there was riding down railed, beak nosed, single fin Swallow Tails. Drew lines, not turns.
Really good stuff from Rusty.
This is very close to my first twin fin…it was a “magic” board…50% sure it was shaped by Neil Purchase when he worked for Nipper…the inspiration would have been Rolf Aurness , and it was Tom Hoy who first brought them to Australia.
Geez RDM , haven’t fins come a long way since then…(lol)…I think it was Geoff McCoys twinnies that started using cant and toe in , to accommodate the narrower tails…MR learned his chops under McCoy.
Maybe a “revival” of such designs awaits. Get onboard early.
Ive done few over the years for grommets …it turns a few lights on for them , beyond the mainstream off the shelf thrusters.
Can you give a few tips kayu?
Low rocker, flat bottom, fins about 6" tall, with the trailing edges about level with the end of the board (as per your comment in a recent thread here regarding twin fins)? No (or minimum) fin toe in and cant?