Ok so on a couple of boards I get the same result when heading deep off the wind.
As speed increases
I can't seem to keep weight on the board.
The board gets squirelly. The tail lifts n the nose starts to dig almost catapulting me.
How do I tune to prevent this?
Is it too much fin?
Or mastbase position?
Both boards go across n upwind well. But deep off the wind they're a hand full.
I can't seem to go as deep offwind as other local speed crew.

Yep, the last thing you want is the tail lifting, and the nose digging.
Basically I think it's because as you go faster downwind, there's too much lift behind you. I can think of a few scenarios.

If you're sailing windward rail down, the wind is pushing the nose down, and the fin is lifting the tail up.
Try sailing windward rail up, that gets wind under the nose and lifts it up.

Fin is just too big, and creating too much lift behind you, smaller fin, or moving footstraps/mastbase back will help.

Negative tail rocker, will also push board lift backwards, lifting tail and pushing nose down.

^^ Thanks. Think I can cross off the negative rocker. It happens on two completely different hulls.
Windward rail I think is flat. But it does lift just before things start getting ugly. Maybe i sheeted out across the chop?? Hard to say it all happens so quick. Don't really have any other fins to try. So I guess that leaves the mastrack to pull back.
So the boards are
150 AHD 77wide 45cm S1 pro n 8.5m Lion
135 Rocket 72wide 43cm S1 evo n 8.5m Lion.
Are fins n sails matched ok?

What Mike said.... too big fin. Maybe drop the boom 1' if the boards a bit flighty and come back on the track

What sort of speed are you doing when things turn ugly? I'd poop myself using a fin that big.

There are a number of things you can change.
- smaller fin
- lower boom
- move mast base forward
- more downhall
Change one thing at a time in small increments and assess the change.
What you are looking for is the Goldilocks setup between too much and not enough lift.

Sailing position is also important. As you bear away and accelerate, lift the windward rail, rotate your hips so you face forward, straighten your font leg and bend your back leg.

Thanks for replies guys. Bit more info. I'm 100kg. Sail Golden beach Qld. Not the most consistent winds. Normally I guess I use largish fins to promote planing. Dredging isn't fun. Speedwise, generally I'm fangin with the local GPS crew. I don't wear GPS. So I'm guessing speeds around 25-30kt when things get ugly. Any recommendations for finsize or type. Seems the Rocket 135 may favour a slightly swept back fin rather than slalom?

fin flex could also have a bearing, a flexi upright fin will give you more vertical lift, this could be increasing your problem.
A more racked back fin will have less vertical lift, but will also shift the centre of effort back, not necessarily and improvement.

Fins are slightly on large side but do-able, especially as you are pretty big guy yes? & sail at a spot with some short reaches & strong current. Personally i'd be on similar fin sizes, -2cm on each maybe if not gusty. The s1's will want you to stay on tail & lift windward rail especially as you change pressures entering run & during lulls or any big lumps.

What is your footstrap position on your back strap, how is downhaul set? Alot of it too is doing it 100,000 times & becoming comfortable with the different pressures you get deep off the wind, more than likely it's a slight technique change.

i'd point the finger at the lion. do have any proper sails?

^^ Hahaha ! Lets Lion em up tiger.

Mkseven. Me 100kg. Rear strap on Rocket one hole from rearmost position. Downhaul on 8.5 was just past maximum. Outhaul at max. Well powered, almost borderline rigging 7.5. But in the lulls I'd then have nothing.

Those S1 fins are powerful fins, for down wind you will get away with 5cm less on both your fins.

your downhaul and outhaul sound fine.

Other stuff worth trying:
Lower your boom (a lot), helps to drive through the front leg.
Lengthen and move your lines much further back.
Move your mast track back.

just my 2 cents work :)

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olskool said..
^^ Hahaha ! Lets Lion em up tiger.

Haha.

But I was being a little serious. The ezzy are not twisty sails and their Coe sits well above the boom.

Not a great combination for speed sailing. A sail with that shape is always going to have a limited top end and be prone to control issues

Ezzy have also acknowledged that with their reworking of the 2020 version.

Could be time to demo another brand just to see. The fin usually let's you know if it's too big because you feel it in your legs and feet.

You could try using a softer top half of your mast to encourage more twist.

^^ Yep I know... They're glorified wave sails. But that's the WHOLE point. I like to see how far I can push it. Generally I've got similar early planing n top speeds as the locals here at GB. Most of em 30kg lighter than me n much better sailors using the go fast gear.
My 8.5 calls for 490 mast. But mine is heavy n made it feel junk. So I use 460 north gold with lots of ext.. Nice n light n gives a lil more twist as you say.
I've got S2 Maui Venoms (correct mast) as well. But compared to the Lion they're a bitch for me to rig n use.
I've used Gaastra Cosmic. Nice.
Bit less bottom end,,bit more top end than Lion. Hard to find.
But
Early planing wins EVERYTIME for me.
No planing = no chance of Top speed.
I'm sure with the right board combo n tuning the Lions can achieve 30kts at GB.

Always, when you tune for low end, you would struggle at the top.
All you can do is dump outhaul and go deeper.

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olskool said..
^^ Yep I know... They're glorified wave sails. But that's the WHOLE point. I like to see how far I can push it. Generally I've got similar early planing n top speeds as the locals here at GB. Most of em 30kg lighter than me n much better sailors using the go fast gear.
My 8.5 calls for 490 mast. But mine is heavy n made it feel junk. So I use 460 north gold with lots of ext.. Nice n light n gives a lil more twist as you say.
I've got S2 Maui Venoms (correct mast) as well. But compared to the Lion they're a bitch for me to rig n use.
I've used Gaastra Cosmic. Nice.
Bit less bottom end,,bit more top end than Lion. Hard to find.
But
Early planing wins EVERYTIME for me.
No planing = no chance of Top speed.
I'm sure with the right board combo n tuning the Lions can achieve 30kts at GB.

Then I'd try moving the mast back in the track.

As you know I also like to run minimal downhaul to get going. What that does is puts a lot of pressure through the mast foot. The solution is to move the mast back to liven up the board by lifting the nose.

It is entirely possible that you have just reached the limit of how fast you can push this gear.

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sailquik said..
It is entirely possible that you have just reached the limit of how fast you can push this gear.

yup. agree. i'm not one to blame the gear but from what has been said i think it is definitely the gear.

Simmer Vmax should be on the radar. has no cams, plenty of knuckle, lots of twist and rigs on shorter masts.

I did 35 on a 68 wide Magic Ride 104 with a 15 year old Neil Pryde Search 5.0 wave sail and a 28 weed fin. So it is possible to go fast enough to scare yourself on inappropriate gear.

I spent thousands on better gear and picked up 2 knots. That's $600 for every 0.1 knot. I should have just gone on a diet.

that's funny rem......being a rocket nut myself ,they are fin sensitive ,since using mine with swept back or weed fins on my WA trip ,they feel easier to push down wind ,I've had 33,5 knots out of my 105 rocket .(can do more ) ..and 32.12 knots on my 125 rocket ..I felt i hit the 125's max .they get there quick ,but pooped myself trying to go further ..as Volume lift off was starting to happen ,plus i was out to sea ...both speeds where done on cheetahs ..since brought maui venoms ,going to give it another crack ,but i agree ,ITS too big on the fin size ..eg.this also works with big wave surfing ,big waves you use smaller fins so you can push it down the wave , because of the extra speed .big fins you get lift off and go straight .

push hard darkman I'm new at trying to break the sound barrier too ,but having a ball trying .

get a GPS watch ..you might be GOING faster than what you think ..

Sailquik, I agree with my old AHD 150. Pretty sure I've found its top end here at GB. The 135 Rocket is my new toy. Only sailed it one session but got into the groove pretty easily. But thought it odd I'm experiencing the same handling issues when pushed off the wind.
Remery, EXACTLY !! I don't have limitless $$ to throw at it. When I started back windsurfing 3yr ago I rode SPEED Raceboards just reaching back n forth. My goal 30kt. Well I didn't quite get there b4 I started sailing shortboards. But 27.3kt on the Canmore screen sure had me grinning from ear to ear.
Tardy, be guaranteed I will be pushing hard trying to find the MAGIC setup for me.

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olskool said..
Mkseven. Me 100kg. Rear strap on Rocket one hole from rearmost position. Downhaul on 8.5 was just past maximum. Outhaul at max. Well powered, almost borderline rigging 7.5. But in the lulls I'd then have nothing.

A bit smaller fin and more downhaul. Try another 10-15mm. Maybe back off on the outhaul a little.