River boat with size and power limitation

Hello, please let me introduce myself
I'm Adrian, I love boating , I live near the city of Brasov,Transylvania, Romania, a great place but unfortunately a little to far from any navigable water.
What I kindly asking you is to help me to find out if the idea of building a cabin cruiser boat is feasible considering the following requirements:
1. The boat has to accommodate a family of four
2. it has to be trailerable, that means a max. 2.5m beam
3. the dry weight must be within 1700 kg so that it can be trailerable with a small size SUV , adding the weight of a 300kg trailer , the dead weight will be 500kg
4. the boat must be no longer than 7m (23feet)
5. the boat has to be powered with a max 20HP outboard engine
6. the boat will be used only on the Danube river and delta, and also on some larger lakes which sometimes gets very choppy.

Before posting I have done a bit of research and with my limited (yet) understanding, the way to go is a full displacement hull, I have no problem with that.
Making some educated guess the max hull speed will be in the range of 4-5 Knots, and the power requirement somewhere in the 10-12 HP range.
One of my concerns is that considering the flow speed of 4-6 KM/h(cca 3knots) of the the Danube river in the middle section , there might be no if any speed reserve left going upstream.
I will much appreciate any word regarding this matter, or pointing to a close to description plan(if any).

P.S. The limitation on Length and horse power comes from the fact that if I can live with them I have no legal obligation of any kind, that means no registration required, no taxes, no insurance.

Kind regards,
Adrian

 

Hi and welcome The Glen L Marine website has 17' cruiser called sea night and this one that arrear to fit your size limits. http://www.glen-l.com/designs/cruiser/dsn-vcr.html These 2 examples can be built lighter and a little larger or smaller and you can design your own interiors to what you like. These boats are simple to build with basic tools and skills and they have a great forum also. took these over and tell us if were going the right direction http://www.boatdesigns.com/17-Sea-Knight-outboard-cruiser/products/355/ http://www.glen-l.com/
http://www.boatdesigns.com/21-Vera-Cruise-trailerable-family-cruiser/products/374/

 

23 feet- 20 horsepower

With 20 horsepower you can get 7 knots (13 kM per hour) displacement or semi-displacement speed without trouble, and normally overcome the river current.

 

Thanks for helping, I already browsed the pictures and infos on glen-l site, probably I will buy the study plans of the 21 Vera Cruise boat, seems to be close to my specs excepting the engine size, but I was thinking also to look after a more contemporary design, eventualy one which uses stich and glue technique..


fredrosse , thanks for the input, so the conclusion is that a semi-displacement hull will alowed me to squeeze all the power out of the 20HP engine and get 7 knots..which would be great.
Regards,
Adrian

 

Check out this thread.

http://www.boatdesign.net/forums/bo...iser-relaxed-cruising-53881-2.html#post747031

 

These Blue Jacket boats are all stitch and glue look at the 24' one and e-mail them if 2' could be deleted forward of the transom. I bet it can be done. Owners are members of this forum. http://bluejacketboats.com/boats-2/