7 foot quad fin Cruiser - advice needed

Hello folks!  I am working on a board and at the last minute decided to try to get some input here before deciding on fin placement and bottom contours…

The board - I am working on a 7’ cruiser type board for small to average days.  7’ x 21" 2 3/4" pointy nose and rounded pin tail.  The tail is 14" wide at 12’ up.  I want the board to naturally fly out of the pocket and then be able to jam a turn back into it…  I guess I am looking for a lot of drive more than anything to fly through lined up or closeout sections of the wave.

inspired by this…  http://www.surfysurfy.net/2013/12/74-christenson-osprey-quad.html

The question - I just want some feedback on my fin placement since it is so critical.  I was thinking about putting the rears at 6 3/8" up and the fronts at 11.5" up toed 1/8’ and 1/4".  I have also looked at the chart for McKee fin placement - it recomends 12 1/4" up for fronts and 5 5/8" for rears…

Also - for bottom contours, I was going to put a light single concave from the mid point to just in front of the fins where it will break into a double that will run out the tail…  Does this sound legit?

just wanted to ask y’all to make sure!  Much thanks for any feedback and for your time!!!

Dunno anything about McKee set-up for fins…but 1/8" tow might be too drivey…I would poke it a tad more to 3/16" tow in…can’t fins , out a little also…ive eye balled mine in, but I’ve heard you can measure it in…

For your bottom I would say a flat to v would be fast and loose (if you plant) in a good solid med amount of v in front of fins! Read up on it in the search…v is not too difficult. I kinda wing it at a forty five with a surform - then block sand…there’s other ways…I’m going to attempt planing it in. Then tuning with block sanding…

I would keep rocker lowish, or natural for a wally wave…you want speed…flat bottom I heard is best for speed…a little roll or curve towards rails might help on turns tho…read up what other shapers do…roll to v, flat to v, flat to concave r common…tri plane hull etc…is going to be more advanced(shaping wise).

what you’re you’re describing is my daily driver for shoulder high to well overhead, though mine is 7" longer…so most likely you’re a front foot down the line driver.

If so, do  consider moving your fin cluster forward, front fins at 12", widens the  accelerator sweet spot, great for power drives down the line from a tad more forward positoin.  Works great with single to double, the forward V between the double concaves makes it easier to roll/pump the turns. 

McKee pulls his rear fins close together, provides much more of a tri/pivot feel to the set-up.  Complete opposite of the ‘put them on the rail’ and claw a turn camp.

Personally like the Rusty set-up, which puts the basically splits the distance between the McKee and ‘rail’ camps.  On my 7’7 RP, front fins at 12 1/4, rear fins at 6 1/8, 141/2" wide tail, rear fins set at 2 1/2" off the rail, 3 1/2" from the stringer.   Plenty of drive, plenty of ‘claw’.  

Why not make it a five fin?  Tri can be more fun on peaky waves, quad mo betta at full throttle.  After trying bunch of fin combos, these days just run my favorite thruster fins up front,  run the matching tri in the rear, or if going quad, use G1000’s in the rears. And on point waves,  really enjoy riding my boards as a five fin with a Nubster fin in the forward rear slot.  all the speed, more vertical bite.

quads=large box of trial fins…lol

 

 

Great input and thank you both very much for taking the time to respond.  It sounds like V needs to be part of the plan.  I may keep the bottom more flat until a foot or so above the fins then add some v with a little double concave that will sit inside the fins.  I did cut the out of a blank with a mellow lower rocker (The Millinium foam 8’10"M).

I hear ya on the quads = large box of quad fins.  I feel like in my limited experience with quads its really hit or miss… but if you get the right fins positioned correctly, it’s good stuff!  I will be using future fin boxes because I already have a  decent collection of future base fins.  I might as well through another box in to give it more options.

Does that rusty set up have 1/4" and 1/8" toe?  I guess that would be kind of difficult to eye…

Anything else guys?  Can’t wait to get home from work and shape it some more!

The roll idea - im going to try myself… what it is: the entire bottom is flat. Now imagine if you just sanded a gradual downwardly angle - fading out to a flat epicenter along length of the board…just for kicks we do 1/8" roll…so technically you could plane around perimeter around whole board…then just blend and a slight roll into a flat bottom! Imagine 2/3 of center across board is “dead flat” , now you got one more third of space…now cut that in half, and put -each half on a rail…cut a band around perimeter 1/8" deep. Stop. Now blend that into bottom - the whole tamale! Hold on, you said you want v. So if you wanted sum roll, just do everything except where you want your v to end at upboard…that way when ya cut in v - you can blend right into your roll! Go with a medium v, I’ve tried shallow v’s and I don’t even think they feel right…a good vee should be noticeable if you take a straight edge in front of fins - it should tilt evenly, and gradually less tilt as you move up towards wide point where your fade out ends… and tail block (tip end of tail), the v should be deepest there. I think that’s a “panel v” -so it’s a panel…

The other type: the v is deepest in front of fins, gradually fades out to a third up board, or wide point if you wanted it up that far? Either or. And then from front of fins out tail block the v fades to flat, or slight v…the flat being more drivey. So take the surform, or block and angle strokes tighter towards stringer as ya scrub down tail…and scrub at a more a forty five up towards wide point, or third up mark depending on where you fade out point ends to…I just hold the surform at a 45 and wing it on a side rail in tail section…stand on op side, wing it, and vs vs. S
Apply more pressure at edges - rather then middle, or youll get a oval pile a chit on ur hands!:smiley: pay attention to NOT flatten the v forming in center line…ive only done four so far! So try several methods to see what you like. Once you put v in - you can probably start your double barrel concave a third up board…and yes, it’s supposed to gradually deepen in front of fins…but there’s no hard rules. Some shapers let their concave deepest out tail block! Some don’t. Try several methods to your boards. I call those “Experimental model’s!” And it’s damn fun, and dread…if you hit magic…I doubt you’ll sell it!

I have not a clue what - Rusty’s fin set up is? I would try 3/16" -just to play safe… 1/8" inch of tow I’m thinking is ok.but probably ideal for a twin. For a quad I would want the front fins more towed @ 3/16". I bet the rear fins at 1/8" tow, and pushed in off rail two and a half inches is probably k. Maybe a quad expert will chime in? You definitely tow rear fins in less.

The Christenson is beautiful.  I wouldn’t call it a cruiser. I’d call it a high line speed machine/ tail stall tube rider. Mike

Rooster - you are definately right!   I shouldn’t call that board a cruiser.  I like “high line speed machine” way better!

I strongly recommend using Probox for your boxes.  I’ve made 11 boards, now, and on all of them the best fin set-up (cant, vertical position, fin choice, fin combination – quad vs tri? More upright vs more rake?  Etc…) has been something other than what I expected at the outset, even when copying a board.

Today I got to finally surf a CI whip copy I made for myself, sized up from a little guy board for a big guy (me), and the best rear fin position was something totally different from what I expected.  I’m very happy with the outcome, but if I’d put in FCS fusion I wouldn’t have been.  The center fin position I liked was well tailward from what the natural translation would have been, taking a 6’ 0" existing board and translating the box locations to a 6’ 7" (the size I made for myself).

Had the cant chosen and box locations been unworkable, or just somehow not right, with the fins I chose I still would have had the flexibility to change the cant inserts and fins.

When making one-offs or doing “R&D,” being able to use Proboxes is invaluable.

Disclaimer:  I don’t work for Probox, have no association with Probox, am “just a guy” like yourself making boards for myself and friends, really wanting them to be good.