ive noticed they dont have tail rescesses on lower volume boards. do they work and what do they do,
I think the more recess the deeper the tail of the board will ride in the water giving u more nose out of the water and I suppose that will make u go a little quicker. No recess and the board rides a little higher and may go over chop better and more control. I would say small speed boards would have the cutouts but not wave boards. Someone will have a better explanation than me Im sure
Im Not sure that cutout do anymore than reduce weted surface area and attract weed
. Some of the F2 boards have trim plates in the cutouts that can trim the board I never tried one though.
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Oh and I'd heard that the cutouts can give a bigger range of fin suitability though I couldn't vouch for that. The new futura etc seem to promote keeping a quiver of fins to enhance the boards usage range.
As far as low volume boards go I suspect they already have a lower wetted surface at the tail so maybe not really needed on them?
How can a cutout reduce wetted surface area? What a load of bollocks.
I suppose the reasoning goes like this:
"If I cut some bits out of the tail then those bits won't be wetted anymore so I'll have reduced wetted surface area". OK then let's carry this on further, and skim 2mm off the entire bottom of the board. Wow we'll have no wetted surface area so will have unlimited top speed!
What rubbish.
If you stop a certain portion of your board from touching the water and therefore giving you dynamic lift then the board will sit lower. This will mean another part of the board that wasn't touching before is now touching. So your wetted surface area will be the same (if the angle of attack of your board is the same and the bottom is flat).
I think the cutouts make the board less 'bouncy' in chop by allowing you to have effectively a narrower tail but with more leverage 'cos your foot is further outboard. Personally I prefer not to have them but each to their own.
Nebs et al.
I have sailed 2 boards with cut out and own one of those small speed thingy's with no cut out.
The cut out boards I have also have the "air pipes"
Vando - happy to give you a run on the F2 SX S when we next sail together. (btw: Manly was crap yesterday!).
Nebs - you can feel the difference when the boards start to go fast (and I'm talking 27 knots+ - less than than and I can't tell the difference) - the tail feels like it is sort of 'levitating' you can feel lift from the tail of the board. - This feeling takes a bit to get used to and you need to have a bot of faith -especially in the fin. Are the designs any faster - I don't really know. When I swap from my F2SX to my Warp Speed In say 20-22 knots, the Warpy only seems to be about 0.5 knot faster on average - and sometimes slower.
I have found the 'cut out' trim/adjustable plates in the F2SX S - nothing but a pain in the proverbial - for me they were making the board spin out - I took them out and the board just behaves a lot nicer (smoother air-flow under the board?).
Can you carry a bigger fin than normal - probably yes, and my experience is that with the cut out board with the wider tail and greater lever moment cos your feet are closer to the edge of the board I usually need to go +2cm than for a narrower board of the same volume.
As or the wetted surface area argument - I'll brush off my considerable scientific talent and think about this some more.
Dr J
i've been using cutout tails for a long time now.
i find they give better response in higher winds on wide boards because there is less tail of the board lifting (railing up)
they have less drag because of the higher aspect drag ratio,
turn better due to an effective shorter water length,
make the boards trim more effectively,
allow a greater fin range to be used.
cutout boards usually work best with slightly bigger fins.
oh, and reduced wetted surface area....
its great to get the response on this one as im tooling up to make a board, and i'm tossing up on wether to use them,ive only ridden two boards with cutout's both were very popular boards and i didnt like either of them, so i appreciate any comments fore or against
When I look back at the cutouts whilst planeing (futura 122) they are well clear of the water so there has to be less wetted surface area hence less resistance which should equall more speed, but then again I'm just a baggy arse plumber so that might be crap too.
well that was one of the boards i tryed futura 115 i think thats the volume,but i must add i didnt use my gear eveyone sets there gear different, to be honest i couldnt wait to get off, but getting my board back was a different story
Tails cut outs to my understanding are to reduce the area at the back of the board, from what I understand these where introduced as boards got wider. Smaller boards generally aren't very wide hence they don't really need cutout outs
I have read somewhere that deep cutouts as well as reducing the wetted surface area allow the tail of the board to dig in when the nose of the board hits chop thus making the board handle chop better, if wide tail was flat the nose of the board would take a bit more to lift up.
The wetted area aspect, in sub planing circumstances deep cutouts by dramatically reducing area at the back of the board can make the board harder to get on the plane, boards with shallower cutouts are not affect that to much (this is why some Board manufacturers have inserts).
Size shape and all the rest of it is way beyond me, Kato (I thunk) played around with all different shapes of cutouts trying to get his most efficient set up for him.
At the end of the day, you either believe they work or you don't, some people like them some don't
Just watched Plug and play 2 this F2 dude says put the cutouts inserts in and the board gets higher out of the water and is easier to control in chop. He has inserts to change the depth, so shallower cutout will make board sits higher, deeper cutout and the board sits lower. Deep cutouts makes rear of board sits lower and nose higher giving you a more free feel most suited to flat water. Thats what he says anyway
good onya willy, now dont wet your self tell me jman what f2 are we talking about, ill have a look at the f2 site
i found the futura jibed like a wide board and could feel the rail;s catching,infact it felt like i was draging a house brick behind the board (maybe the cutouts) the second was a jp 108 lt 2008 slalom again it felt like a wide board jibeing, besides i allso didnt like the deck.
tell me more about the duck tail Gestalt i'm all ears ,are there any production boards that have a duct tail let me know and ill check them out,
there,s one consiation about sticking cutouts in is you can allways fill them in and play around with them after the board is made, not so easy the other way around
One day slowboat explained it to me while I was trying to figure out how to improve the trim on my speed board.
Any lift behind the rider will tend to flatten the trim of the board, (force the nose down).
So if your board is riding too flat, you may have more wetted surface area than you need.
So yes cut outs CAN reduce wetted area, (sorry nebs).
It's all about optimum angle of attack, if the angle is too great that will slow you down, (pushes water).
If it's too small that can also slow you down (too much wetted area).
Tail rocker can have the same effect as cutouts, a bit of tail rocker reduces lift behind the rider, helping to get the nose up.
the rocker on my speed board has a straight section at the back 1.1m long, so when it sat flat, it had a lot of wetted area. (entry between front foot and mast) When I put the cutouts in the entry point moved back to just under the front foot, and I got better speeds.
Thanks Slowboat!!!!
Yep, agree nebs.
My back strap is already directly over the fin, didn't like the idea of it going any further back!
Think this was discussed before, and it was mentioned that the US navy found an angle of 7deg was optimum for their planning hull boats, lets the wetted area reduce with speed increase.
