BoofHead65 said...



At what length does it become neccesary for a rudder system?

Have always been fascinated by the SUPS at downwind events and am gearing up for a Kaholo 14 build.
I've designed a 15' craft as a potential strip built project if I get in to it and can easily lengthen the design.
I'm not interested in organised races, I just want to go fast. Flat/bay and open ocean. I weigh 95kgs @ 6'3". If I go with building a long board, I would rather not have to stuff around with a rudder system as I expect they would be hard to source and pricey.

Cheers

I reckon if you're going for big open ocean conditions and DWs in big swells then maybe go for a well designed rudder system, but if you're after fast, flat water cruising don't bother.

FWIW I've taken the rudder system off my 17 foot Naish and had 2 fin boxes fitted - one forward for a small ventral fin and one for a keel fin in the tail. This works very well for me and the way I use the board as a flat water distance/cruiser.

The setup aids tracking better than the (too small IMO) Naish rudder, especially in messy side chop. It calms the board right down in the confused short-period slop we tend to get a lot here in my part of Melb. It allows a more forward stance on the board for better trim and improves the stability of the board enormously (it's a pretty stable board anyway but when doing distance runs the extra stability helps a lot when a bit of fatigue starts to kick in). The ventral fin also doesn't seem to adversely affect turning...step back a bit and it comes up enough so it doesn't get in the way.

Your conditions and use might be a different to mine but it's an option worth a look. The fins come from Larry Allison.

Here's a couple of pics







(Yep, I've mowed the grass weeds since taking those pics)

hoagie said...
You might want to get rid of that big spider web on the fence too

That would just give the spiders another excuse to be inside on the Wii.

BoofHead65 said...


So, optimal length for speed without a rudder?

depends...how long's the string*

Luc Longley's DC17 doesn't have a rudder. Exocet (euro mob) make a fixed-fin 17. There are at least a couple of fixed fin 19 footers (with and without ventrals) that have been spotted over on the 'zone.

* This isn't a non-answer. It'll depend entirely on you, how big you are & what you're going to do with the board and where. If you're designing and building the thing yourself, why not put in a rudder system and a couple of fin boxes...cover all your bases (I've doctored my 17 but I've left it so the rudder system could go back on if I feel the need)

HumanCartoon said...

BoofHead65 said...



At what length does it become neccesary for a rudder system?

Have always been fascinated by the SUPS at downwind events and am gearing up for a Kaholo 14 build.
I've designed a 15' craft as a potential strip built project if I get in to it and can easily lengthen the design.
I'm not interested in organised races, I just want to go fast. Flat/bay and open ocean. I weigh 95kgs @ 6'3". If I go with building a long board, I would rather not have to stuff around with a rudder system as I expect they would be hard to source and pricey.

Cheers

I reckon if you're going for big open ocean conditions and DWs in big swells then maybe go for a well designed rudder system, but if you're after fast, flat water cruising don't bother.

FWIW I've taken the rudder system off my 17 foot Naish and had 2 fin boxes fitted - one forward for a small ventral fin and one for a keel fin in the tail. This works very well for me and the way I use the board as a flat water distance/cruiser.

The setup aids tracking better than the (too small IMO) Naish rudder, especially in messy side chop. It calms the board right down in the confused short-period slop we tend to get a lot here in my part of Melb. It allows a more forward stance on the board for better trim and improves the stability of the board enormously (it's a pretty stable board anyway but when doing distance runs the extra stability helps a lot when a bit of fatigue starts to kick in). The ventral fin also doesn't seem to adversely affect turning...step back a bit and it comes up enough so it doesn't get in the way.

Your conditions and use might be a different to mine but it's an option worth a look. The fins come from Larry Allison.

Here's a couple of pics







(Yep, I've mowed the grass weeds since taking those pics)

i have done the same thing with my 17foot glide, i dont have the second fin box but that does seem like a good idea for flatwater cruising but i run a 12inch keel fin so it keeps it prety straight, i also have the fin box behind the rudder system so i can put the the rudder back in if i want, it suits it for what i want and i have no problem steering or turning to much, maybe just try a few boards with or without rudders and see what you like, or you could wack a rudder and a fin box and go with what you like,

Jarryd

OG SUP said...
Hey HC have you tried a ventral fin with the rudder fitted?

Thats my next experiment with my K15

Phill

I haven't but my mate has, he's tried it with the rudder and a ventral fin (he "borrows" the centre fin out of his wife's Mana, not sure exactly what size it is). I haven't seen it in action but he reckons with full rudder it pivots around the skeg and just about turns in its own length.