My max speed is faster in small harbor chop than it is in flat water (a few meters from a sand bank).

I'm 70kg.
With 110L Falcon, 7.8 overdrive, 44 venom fin, I often get 32knots in harbour chop, but only get 31knots in flat water.
With is87, 6.6, 34 venom, I get close to 34 knots in harbor chop, but only get 32 in the flat.
I have not tried the is87, 5.4 and 29 venom in flat water as its been a poor season for wind (could have used this once a week last season).

I have confirmed this with GPS and sailing with others, where sailor X is right on my tail on the flat, yet I easily get away from him in the chop at the end of the run (he slows down and I speed up). I have tried all mast track and boom settings (track at or near back and boom at chin height seems to work best). I'm assuming smaller fins is the key.........and possibly a smaller board for the 5.4.

I find the C3 venoms are great in chop and the board flies nicely off them, but in the flat they seem sticky and the board is not flying off the fin. I'm sure others have got venoms to great speeds but are they known to be slower in flat compared to other fins?

Any recommendations in fin type/size for the is87 on 6.6m2 koncept and 5.4m2 koncept (we should get some good wind soon!) ?
We don't have weed issues here, but a shorter fin would help me get closer the sand bank and/or allow more sailing time in low tide conditions.

Any other tips for maximizing speed on flat water?

I'm relatively new to Slalom, started last year and I don't feel enough competent to recommand or propose, anything. i need to ask the question for my personal knowledge. 44 on a 7.8 and 110L is not considered overfinned even in very light wind? Your speed is amazing so I guess not! I used 38 to 42, mostly always feel better with the 40 even in light wind with112L jp and 7.8 evo, my fins are slalom fins from makani in G10 but going in carbon soon(ordered). Thanks

Good question and you helped me find a mistake! The Venom I use is a 42CM not 44cm.
Venoms are not powerful for their size and it is recommended to have them 2cm longer than you would otherwise use.

Hope your new fins give you a step up in performance. I have found fins can make a big difference.
I got my 110 Falcon secondhand from a national racer and it came with the fins he used, 38 and 36 Vector Volt G10. I tried the 38 with my 7.8 and I was almost getting to 30knots, but upwind was a struggle. I slotted the 42 Venom in and straight away got 32knots, the board was flying off the fin better so when a gust hit it accelerated away....big smiles that day and many days since then. It has also allowed me to take the 7.8 into higher winds than I thought possible.
The Volts must be good fins and I will keep them for more testing and/or might suit a newer board in the future.

The is87 and 34 venom has the same flying off the fin feel and despite the rougher water conditions I can hover over chop with realitive ease. Ultimately, the chop is slowing me down and hence the desire to sail on flat water to see how fast I can go........I'm perplexed why I'm going slower in flat water

There are differences in tuning between flat and choppy water.
In chop you want the board to sit relatively flat, so that it can ride over the chop.
This can lead to too much wetted area when sailing in very flat water. So you need to be more on the tail, moving mast track back is probably the easiest way to achieve this. But there's also foot strap position and sail head twist. A powered up sail head will push the nose of the board down, so more downhaul and using the lower leech hole for the outhaul, will twist the top of the sail off more, helping the nose to rise.

The other thing is fin size, in chop you need a big fin to avoid ventilation. On flat water, this isn't so much of an issue so you only need a big enough fin to trim the board and get you back up wind. I'm a tad lighter than you and using weed fins, but I use a 26cm with a 6.6. and if it's blowing, a 20cm with a 5.4, if I'm just interested in going downhill for speed on flat water.

But I suspect your main problem is the board is sitting too flat in the smooth stuff, but is close to ideal in chop.

Wow Mike that's probably the best description for how and why speed sailors tune their sails in this way that I have read. Thanks

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decrepit said..
A powered up sail head will push the nose of the board down, so more downhaul and using the lower leech hole for the outhaul, will twist the top of the sail off more, helping the nose to rise.

I realized that mid season, this is really not intuitive! (downhaul more to get nose up even when wind is not that strong.)

I also read that a good 38 Carbon Fin would feel like a 40 G-10, would you agree?

nord_roi

Thanks for your great reply Decrepit.

You have reminded me of what tools I have to get more lift in flat water. I guess over the years as a light weight sailor, control in chop has always been a priority and my sails have been tuned accordingly. I will try playing with the tuning of the sail and see how I go. Lucky for me the Koncepts are easy to downhaul with a harness hook while sitting on a sand bank.....ie don't need a winch

When thinking back to my last session I had on flat water, it was 7.8 or 6.6 conditions and I decided for the 6.6 and purposely set it on min downhaul for extra grunt. The board was very sticky on the flat despite mast track and boom setting changes. It just didn't go through my mind the lack of downhaul on the sail could be a contributing factor.

I have no experience with weed fins, but is a 26cm weed fin approx equivalent to a 31cm standard fin with less rake? and 20cm weed fin approx equivalent to a 24cm? Do you use these fins with a speed board or a small slalom board?

Depend of weed fin. Makani just created new custom carbon weed fins and apparently if you need a 38 reg it would be a 38 weed. I just ordered one(i'm in canada, so everything is frozen). I also purchased the sail and board from a US pro sailor and he was also recommanded a 38. I was not going upwind enough in ligh wind so the 40 is way better unless it's super windy(for my level). The Evo8 was requiring a 430 but the Pri Sailor was recommanding a 460. However I'm 68-70 kg as well, not sureci did a good move...and requires a winch, man that sail is hard to downhaul!!

i purchased a 107 is and a 7.0 mach1 and selling the 112, a tad big for my taste, hopefully the ISonic will be what I needed, at that price better be!!!

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srtgumbee said..
>>> I guess over the years as a light weight sailor, control in chop has always been a priority and my sails have been tuned accordingly.

As a 65kg sailor that's also my problem and why I'm a flat water junkie, and why I always use weed fins, cause that's where the flat water is.

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Lucky for me the Koncepts are easy to downhaul with a harness hook while sitting on a sand bank.....ie don't need a winch

Absolutely!!!!!! I just love my koncepts

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is a 26cm weed fin approx equivalent to a 31cm standard fin with less rake? and 20cm weed fin approx equivalent to a 24cm? Do you use these fins with a speed board or a small slalom board?

Mainly no, but depends on the design of the fin, there's some low aspect ratio, highly raked fins that have massive area for their depth. That have equivalent lift to a longer standard fin.
But conventional weedies of about 45 degree rake are sort of equivalent to the same depth pointer. A weedy has more area, but is less efficient, these two effects cancel out.

Not sure about defining speed/slalom boards. The 26cm I'd use on my 53cm wide board with 6.6/6.2 and a 24/20cm on my 48 with 5.8/5.4 and 20/18cm on my 43 5.4/5.0 for standard 45deg weedies. On Monday I had a 16cm on my 38 with a 5.0

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NordRoi said..

I also read that a good 38 Carbon Fin would feel like a 40 G-10, would you agree?

nord_roi

Again depends. carbon is definitely stiffer than G10, but G10 seems to vary, some G10 fins are easily stiff enough but some are real sloppy.
So you could have examples where you couldn't tell the difference, but others where a 2cm difference feels about right.

And the more the fin is raked the worse that difference gets. At 45deg the fin should have almost zero flex, put it across your knee, if you can bend it more than a mm or two, it's not going to be a good weedy.

gumbee, check out these posts.
www.gpsteamchallenge.com.au/sailor_session/show?date=2018-02-19&team=105

Tomski would be around your weight. Strop would be much heavier. They are both using 6.6s and tribal weeds from 23 to 29


And it looks like they were going for hours and alphas, not tuning for all out downwind speed

On Monday at Coodanup I had too much sail up (for me) and was overpowered getting upwind but once I got into the smooth stuff I bared off ok, but nothing much happened. I was in a rush and had left my footstraps inboard and forward, I'm wondering if the board was just too flat. Also I reckon I've gone faster on a 28 weedy than a Delta XT 18. With the 28 I rode up on the fin barely in control and seemed to get a better peak speed.

(edit: just saw the XT50 post, clearly the fin was not my problem)

111litre board 68 wide with 7.8 and 36 tribal powermax is a good combo but when fully powered would be better with a smaller fin say 33cm. With a 6.3 and 54cm wide board a 23cm tribal sym speed works very well. I am over 100kg. When you are powered up fins can get a lot smaller. At 32knots speed you dont need much fin. Try a 32 to 36cm fin and see what happens. Decrepit is right with more downhaul and move mast track back. Also roll the board over more in the flat to fly on the fin.

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Piv said..
Also roll the board over more in the flat to fly on the fin.

This is what got me hooked on Slalom. I still love wave sailing better, but on a bad wave day, I don't mind geting the slalom rig and go in the outside and play with the big rig on the fin!

But since it's for flat water, a super stiff fin would be nice, but a little flexy at the tips would give better control and would be better in choppy water and that would not count in the flex test you were mentioning(fin on knee and apply pressure <= 1cm of flex)?

This is all great info, and at least I have some things to try. Good to see what some of the fast sailors are using......seems the smaller (board, fin, sail) you can go, the faster you can go. I will consider a speed board if/when I get the is87 dialed in on the flat.

Those that are using weed fins for sails 6.6 and below, are you doing so because of the weed OR is it because of shallow water and/or they work well with wider (compared to speed board) slalom boards?

I ask this because if we talking tribal speed fins for a small slalom board (eg is87) with NO weed, which would be best to try, a Tribal weed or Tribal SYM Speed?

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srtgumbee said..
This is all great info, and at least I have some things to try. Good to see what some of the fast sailors are using......seems the smaller (board, fin, sail) you can go, the faster you can go. I will consider a speed board if/when I get the is87 dialed in on the flat.

Those that are using weed fins for sails 6.6 and below, are you doing so because of the weed OR is it because of shallow water and/or they work well with wider (compared to speed board) slalom boards?

I ask this because if we talking tribal speed fins for a small slalom board (eg is87) with NO weed, which would be best to try, a Tribal weed or Tribal SYM Speed?

all the flat water spots have weed. A lot are very shallow also and the raked weedy gives you a margin of safety if you hit the bottom.
Tribal weed or ultra weed. - the ultraweed is more versatile in the really thick weed and sheds Safety Bay weed better

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NordRoi said..
but a little flexy at the tips would give better control and would be better in choppy water and that would not count in the flex test you were mentioning(fin on knee and apply pressure <= 1cm of flex)?

The flex test is for raked fins, upright fins can handle a bit of flex without increasing drag too much, can even help with a bit of vertical lift.
But if the fin is raked back both flex and twist just create drag and loose lift.

So if you plan on reboxing an upright fin to turn it into a weedy, this is where the flex test comes in handy. Also if you are buying an unknown weedy.

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srtgumbee said..
This is all great info, and at least I have some things to try. Good to see what some of the fast sailors are using......seems the smaller (board, fin, sail) you can go, the faster you can go. I will consider a speed board if/when I get the is87 dialed in on the flat.

Those that are using weed fins for sails 6.6 and below, are you doing so because of the weed OR is it because of shallow water and/or they work well with wider (compared to speed board) slalom boards?

I ask this because if we talking tribal speed fins for a small slalom board (eg is87) with NO weed, which would be best to try, a Tribal weed or Tribal SYM Speed?

Small boards are only faster if there is enough wind for them!
And if you are sailing against a speed bank that has no weed (like Sandy Point) a Tribal Sym Speed is probably faster.

But as Anita says, most of the speed spots here are shallow and weedy. And for the places that aren't weedy, it's not worth retuning for an upright fin, so I just use my least raked weedy.

Preferably only use weed fins when there is weed. Usually an upright fin is better all round unless there is weed. That said the tribal weed speeds are very good so if you do sail in weed and no weed and only want one fin, go for weed type.