Hi All,
Great news about RAID Romania, Gyula!
The idea of 4mm sides and 6mm bottom is ok if
The boat is never going to be used on a quick moving river.
The 4mm plywood is good quality. It only makes sense if going for lightness. This is admirable!
Some might think that you can build with lighter ply and add fibreglass to make it stronger. But this is a bad idea.
Fibreglass is much heavier than everyone expects. It will increase the weight so the boat is difficult to carry for one person.
Fibreglass is more expensive than buying 6mm ply.
It adds a lot more work.
I never suggest heavier than 75gsm cloth for hulls. We found it is as strong as 150 or 200gsm for boats this size.
Kayak designers that suggest more than 75gsm are wrong unless boat is ocean wave surfing onto rock.
Michael