Making myself up a new groveller for summer. it’s 5’2 x 20 1/2 x 2 3/4, kinda simmonsy but a bit more pulled in and HP. All of my other grovellors have been quads, but thinking I want to go twin fin plus trailer for this one, but not 100% on placement as I have very limited experience with twins.
As a bonus I have a set of long keel fin boxes, and the keels to go with them, that will also take regular FCS. These boxes give me about 1 inch adjustment forward and back with both the Keels and regular fins.
I’m thinking of putting them at 6 inches up, with the option of sliding fins forward to 7 inches, with 1/8 toe in and 4 degree cant. The trailer box has 1/2 inch adjustment and i was going to put that at 3" from tail so it can be slid forward to 3 1/2". The plan is to ride MR TFX’s at 7" with a small trailer, and have the option to ride the keels if its really fat. I’ve attached a screen shot of the plan. What do you guys think of this placement idea?
looks fun are they surfinz boxes? No good advice on placement except it looks mini like so maybe further back? They twins on mine sit at 5in and the keels would be close to 3 and there are no issues turning it. In saying that though I have wondered a few times how out would go with them up further.
like 17.25" tail, 20.75 width, 15" nose, thick like a simmons, same goal as yours I suppose. I’ve got the sides at 11" up, center 3" up. My tail seems to be more pulled than yours, as I went more closer to a standard thruster design than you it seems. I’ve got the futures twin and trailer.
My logic was, since the tail is so wide and thick, I don’t need them as far back to help me push along or something. I find that if my foot is right at the back, against the kick in the traction pad, I can pump it well and pick up speed. It also cruises along just fine if I just relax and go and stand a bit more off the tail. I also like extremely loose boards, and mine fits the bill. No effort to make it squiggle around on a gently sloped face, but it can fly in steeper waves.
I honestly have no idea on that though. Maybe have them further back than mine? I don’t think my placement is that bad, but I’ve never tried anythign else on that board so I wouldn’t know. There is noticeably less drive through turns, especially when going frontside, when the center fin is missing. Not an unexpected result. I’ve never had a board with the fins so far back, but I can tell you that I don’t have any major regrets with my placement.
with where i want to put mine, it would more be a matter of putting a set of front plugs to turn it into a twinzer, the placement for the twins would be too far back to be the fronts in a quad setup, and probably just too far forward to be the rears… hmmm maybe push them back even further.
Paging Greg Griffin for some input - i know he likes his twins way back.
I’m in the middle of finishing a 5’4 mini simms twin, very similar, and spoke with finbox larry of pro-box on the phone. This is my first time putting in anything but a single fin box, so he gave me some guide numbers, and heres what he passed on if its any use to you:
The fins I'm planning to use are 4” deep and 10” Long, Half Moon keels
Using a probox system, with the 4 degree cant insert
The back edge of the fin should be 4” up from the tail, and 1” off the rail
maybe it might be worth pushing them back a tad, although I am designing it more for the MR twins plus trailer than keels, i want it to be compatible with keels for certain occasions.
I really like the curve on this outline. I can see blowing this up to around 6’10" x 24" x 3.5" to make a mini SUP for my granddaughter in EPS. PM me if it is cool for me to use your file.
thanks barry - those numbers help a lot - the plan shape looks pretty close too.
have you tried riding it as a twin in the back plugs of the 5 fin model?
i’m not really planning on riding it as a tri fin, more a twinny, but want the option of throwing in a very small trailer or nubster with the twins. you reckon between 6 & 7" would work for that? rode a mates board on the weekend that had thruster setup but he rides it as a twin and it was just way too loose.
