Widow maker fin placement

so I’m keen to for suggestions for fin placement. 

10 inch box with side bites.

any suggestions.

side bites will be 1 inch from rail. 

Board is 7’0” by 21”

Sweet shape  

Hi - ‘Widowmaker’ specs are not set in stone.  I would put the center box as far back as you can.  With the trailing edge of sidebites a bit farther up than a typical thruster, you should be in the ballpark.  With toe-in at about 1/4" and cant set so the tips are about 1"+ farther apart than the bases(not sure on degrees), again,  you should be in the ballpark.

Once again, nice salvage job on that board!

Placement on a true “Widow Maker” (ala Parmenter) are a little perverted in comparison to a 2 plus one.  On that size board you could drop back to 4 1/2 up 5 1/2—-6”.  Hulls are sometimes further forward than that.  Sidebites would come out at 15 1/2”—-17”.   Generally on a true “Widow Maker” the sidebites are pulled back a bit and if you get them too far back may conflict with the single fin.   These are general guidelines.  Best thing you can do is set the boxes on the blank using these guidelines and “eyeball” their placement.

Cheers mate

Thanks boss

I’m not sure how much this helps but I have a photo or two to add.  The big one is a Dave Parmenter model of a friend.  The fin base is approx. 6".  The other one (of Neal Purchase) is snagged off the net.  He is reported to have worked directly with Parmenter on some of that stuff. I think McDing’s idea of eyeballing is perfectly valid as, unless two boards are otherwise identical in every way, using a micrometer for fin placement isn’t going to do you much good…


Thank you John.  I think from John’s pics you can see what I was getting at.  Dimensions are exaggerated in photos, but you can see that the center fin and sidebites are grouped a little closer than they normally would be on say a 9’0 single fin with sidebites.   I Don,t think it is a case of the sidebites being further back, but a case of the center fin being 2 or 3 “ forward.  The leading edge of the center fin gets into an area where it is forward of the trailing edge of the sidebites.  I can see how this would work well on shorter boards like 7 and 8 footers.  My standards on a longboard 9’ —- 9’6” would be 5 or 5 1/2” —-6” from Tail for a center box.   15 1/2”. 16”’ 16 1/2” or even 17” for Island style waves to the trailing edge of my sidebites.  Best to use thes #’s as reference and “Eyeball” it.  Strictly said;  “numbers don’t lie, but they can sure look like $#!t”.

There’s an article somewhere with Dave talking about the widowmaker, maybe an old Surfer’s Journal. I think he was saying he places the side fins so the rear edge is at the front edge of the center fin. Where you place the center fin is something I don’t have an answer to. I’ve been setting up the rear to be able to have a single or thruster.

Dave has a good website with a lot of information. I’d also take a good look at the Takayama Howard Special boards.

Another very nice looking board.

Widowmaker - twinzer- twingle 

ive yet to get it in a longer board but I really feel it would perform really well

Ruined a nice board with that billy setup.   Slow turns, drag and weight.  IMHO.  Based on what others who have tried that have told me.   But I don’t  need feedback to know how that would ride.  I’ve surfed a variety of boards since I was 15 and am 70 now.  One look at a setup like that would tell any good surfer what it would do.  It’s not a Widow Maker or a Twinzer, so is it the famous “Twingle”?  Lol

All hail mcdings “humble” opinion hahaha!

Somebody needs to say it.  You don’t have to hail anything.  Taking for granted that a set up like that would work just because it’s design comes from a certain Swaylocks personality;  That’s the “hail”.  And by work I basically mean an improvement over any existing setup.   I always say the “proof is in the ride”.  If It’s the be all end all,  you’ll convert and ride nothing else.  Otherwise it will wind up on a rack in the garage after a month and a couple of go outs.

So I made a call based on all your feed back and that of a few others I respect. 

You’re all legends.

But now I have this issue.

Could be a dumb question but what’s the minimum depth I can route out for a 10” fin box. You can’t see very well but the tail is pretty thin. Tail at 4.5 inches is 7/8 thick. There is another pic there showing the box depth.

 

Sorry if the picture files are a little large.

 

Hopefully get to do the side bite routing and laminating over the next week or so.

I’ll keep you all posted. 




You don´t want to ruin your artwork.

So I think you want at least 1/8" more taildepth than your box depth.

Depends on how confident you feel with the router.

Even 3/32" should be ok with a sharp routerbit.

I would route a slot shorter than the box. Have a look with a light and measure, and then decide if I want to risk to extend the slot further back or if I´d rather route the rest of the needed length further to the nose.

I have routed slots leaving less than 1/16 in stringerless EPS, almost paperthin. But that would be hard with a stringer.

Going through to the deck would not be a big deal on a white blank for me, so I risked it. It worked out. But that´s not a risk you want to take with your artwork.

Another option for thin tails is grinding down the box height a bit at the end.

Seems you got a rather deep box. (seems to be no edge to grind down and the measured height seems to be your final height)

My fins unlimited boxes and some other no name boxes I have are 1" deep quite exactly.

Maybe you win 1/8 inch by buying another type of box ? I attached a picture of the other boxes I use beneath the FU boxes. All exactly 1" deep.

Anyway, you will route away like 99% of your stringer. Don´t know if this is a big deal in a PU blank. I guess it is.

With the artwork already done, it would be a pita to add stringer reinforcements next to the box.

But on a white blank with such a thin tail, I think I would consider adding reinforcements.

But that´s just 2c of a landlocked backyard kookshaper…Take it with a grain of salt.

[Quote]I’ve surfed a variety of boards since I was 15 and am 70 now.
[/quote]

And still shaping, surfing, and rattling cages?? Amazing!!

The box looks a bit taller than some.  No matter.  Slide a fin in there and see how deep your fin sits.  That might give you a better indication of how much you can shave off the top before or after installation.  You can often move the box back a bit farther than it seems - just don’t go through the blank.  A rule of thumb ‘back in the day’ was to take a set of calipers to the box, add 3/16" or so, slide it over the tail and where the calipers grabbed, that’s where you routed your slot.  Case closed. 

As mentioned, you can also shave the box down a bit so it fits a shallower routed slot.  Or leave part of the box sticking out during install, sand it flush, and live with the fin sitting a bit proud.  I’ve also sanded the fin tab down a bit so it isn’t sticking out of the slot so far… if your screw tab is in the trailing edge of the fin, the pivot pin in front takes any impact anyway.

Just looking at it, I’d say your box has at least 1/8" extra to work with.

PS - I wouldn’t worry too much about the 4.5" from the tip placement.  As already pointed out, it ain’t set in stone.

Sk8, that box is not doing you any favors- I do not see a resin dam nor tabs/ears for setting depth. I gave up on generics and just get the real Bahne boxes (Fins Unlimited).

I have one in front of me and it is measuing .885" [22.5mm] inside depth from bottom to board surface and its setting depth would be about .980" [24.9mm]. from outside bottom to the bottom of setting ‘ears’.  Without changing the depth or size of the box one would need like 1 1/16" [27mm] of board and a steady hand to rout .985 [25mm] deep. I have yet to try that on a stringered board

Are you thinking pre or post glass install? If it is all that thin, wondering if post-glass is the way to go so the top does not want to ‘blow out’. Would be a shame to muss up the artwork…

The Bahne box is made from three horizontal pieces (bottom, sides, resin dam w/ ears) so there are seam marks that show where all these are from the outside too. Maybe if you can see the seam from bottom to side on yours yours, you could measure up 22…5mm from the seam and call that your minimum set line.

Or, you could take the box and plane it down from the top until your fin fits and then tack glue a couple stir sticks the short way accross the top to act like the ears. Measure depth from top to bottom and rout slot to match. Less mathematical but would make sure fin, box, and board cooperate.

 Nice looking board, hope the install works out well for you. None of this blowing off the stands stuff and the like…

All good info.  But put simply;  Determine where you want the backend of the box to be, check with calipers to see if you have at least one inch thickness at that point.  Be careful when you set your router.   If you are right at one inch, you will need to set your router shallow of that so that you don’t rout thru the deck.  On a thin board you can sometimes move your fin box forward and gain enough thickness to get the box in with room to spare.  Yes you can grind a little off the bottom of the box.  You will be grinding off the top.  What distance from the tail are you considering?  How thick is it at that point?  With a Bahne/Fins Unlimited Box I shoot for leaving one inch thru the rear of the box.  Those Aussie boxes are probably one inch on the button.  Once you’ve gone thru this, it teaches you to plan as you shape.  Reread;  I think 4 1/2” is toooo far back.  

Use a white box it won’t show thru the deck.