how small can a boat/jetski be?

Ive been looking for some really small boats or jetskis or build it myself but dont know where the limit for have the whole thing floating.

I weigh about 70 kg, if i put like a 2 hp engine on, it weighs about 15 kg with fuel.
The hull f the boat/jetski might weigh about 30 if its made of fiberglas/epoxy.

so about 115 kg total.

Here is the bomboard: http://www.xconomy.com/wordpress/wp-content/images/2014/04/BomBoard-Workshop.jpg

length: 213 cm
width: 90 cm
height:50 cm
total weight: 75 kg

here is a very small boat. Dont know the dimensions of it but probobly around 180cm long and 80 cm wide. He seam to sink only about 15 cm in the water. Pretty good floating capacity i think.


So if i want to build my own, how would it look liketo have the best floatingcapacity? In terms of stability i will just add some small pontoons on each side. I just dont need to get wet when sitting on it.

 

I think you should make a short list of what you require, in terms of performance etc. A jet-ski is a fairly complicated piece of equipment, and replicating one in a scaled down form would be as difficult as making a full size one. But, if your requirements are for a simple one-person small watercraft, without the performance characteristics of a jet-ski, things become much easier.

 

Major problem for me is to have a light enough engine thats good enough. And i need it to be placed like a jetski, in horisontal position in the middle of the boat and not have it mounted at the end like a regular boat.

My requirements are an engine that can be mounted in horisontal position and dont weigh that much. We can say i have a weightlimit of about 25 for the engine. As for speed.., yes id love to make it go as fast as possible but for me even 15 km/h would be enough. This has a topspeed of 40 km/h and except its a bit too long, it fitsmy needs perfectly 2:40 min intihs video:

I think the engine or the seat is way to far back and half of it is in the air. Its 2.47 long, 70 cm wide and weighs 85 kg.

If i had an engine like that or at least a bit close to that, i would just need to make a hull.

 

Why must the engine be mounted in a "horizontal position" ? Why must it be in the middle of the boat.? If you want the boat to be a small one then you will have to share the space with the engine, in the middle of the boat.

 

i will have a seat over it so i dont have to share space with it.

The reason is it will be a ampibious "boat". It will have wheel and so at the end so i cant fit outboardengine on the same place. i will have a 39 cc engine for it to work on land and it would be very heavy on in the back end it there where like 30 kg there.

 

Check out the wildthing - an older (late 1990s) commercial design by wahoo. Small, fast and stable. You used to be able to play in the surf in them.