Hi guys, I need your help

A friend of mine just started making his own surfboards & SUPs. I asked him to build an epoxy kite surfboard but first I need to choose the optimal shape.
I want a responsive surfboard that works well in onshore medium waves. Right know I ride a Liquid Force 5'10" -18' 1/2 quad which I love it but I think it doesn't has the ability to make tight and agressive turns... Maybe the new board should be a little bit shorter and thruster fin set up.
Any suggestions?

By the way, I only ride strapless so inserts are not an option.

Thanks in advance!!

Here ya go:

Thanks KitesurferRO! I appreciate your idea.
Any decent response?

If a thruster, not too much rocker but some hips, and use a smaller center fin (example 4.5" side fins, 4.3" center).
But quads can be great for tight slashy turns actually, no?
they have the reputation for that at least, and quad is usually popular for onshore winds....
BTW are your fins glass or plastic?
If your board has plastic fins, that could be making it feel mushy in turns...
First, why not try smaller rear fins in your quad?
That could loosen it up if that's what you are after.
The again maybe you need a new board.
Personally, I like thrusters myself....
Anyway it is all extremely subjective.
I would say make sure you know what you want before getting a custom from someone who has never built kite-specific boards, or it will be a shot in the dark, unless you just have him copy another board.

Hi BWD,
The fins that I am actually using on my quad look very crappy and are made of plastic. Maybe I should try some smaller fins but I don't want to spend money on this old board, it still works nice.
This guy is also a kiter who has built some kite surfboards, so I trust him. I'll try to test some production kite surfboards, Naish Skater 5'9" or North Wam are my candidates.

To kite and carve hard with power, at least the side fins really really should be glass or better not polycarbonate or nylon cheapo plastic fins (ie fancy fins, glass carbon, g10 whatever).
I would highly recommend you buy at least a pair of strong stiff glass fins for the forward pair of your quad and ride it some more before ordering a custom.
Keep the plastic ones on the rears if you want, or get a full quad set of glass ones, with the back ones not too big.
You may still want a new ride, it's only natural
But you may get a lot more out of the board you have, and learn more about what you want to complement it, rather than just replacing it.
Could be the best $50-100 or so you spend on gear this year!
For a quad it may be worth it to get the fancy foam cored resin infused kind, 4 glass fins is heavy...

You guys convinced me, I'll change the two forward pair of fins. But I'll order a new thruster board

Thanks!