New here, thinking about boat

Hello, years ago I was a machine engineer on a ship. I m now thinking about building a boat to live on and travel.
I can have steelwork really really cheap, so I m sort of trying to fit the hull into something easy developable. She is rather narrow, 36´ long or around, wont be very spacey inside, but life is a compromise. Also flat sides and lots of flat panels for easy build.
This will never be very fast, but very efficient - I think it should need only about 12-14 hp to go at 6.5 knts continuously. So with 35 hp engine for emergencies it should take only about 2 l of diesel/hour. This will give it huge range - at expense of speed off course.

This is hull only, I shall draw the upper structure in autocad later, neverthelless its gonna be something like "dieselducks".



Could you possibly comment, or point me to similar ship. I cannot make her any faster that short cannt I?

Thanks Jaro

 

The bottom between frame 0 and frame 2600 does not seem right, and between frame 9600 and bow is not developable. You should work it a little more.

 

I know about bow, I thought that will be only dificulty, though there is a steelyard near which can bend most any plate shape.

What do you mean about botom "does not seem right"?

This is by no means fisnihed, its a starters, model in works.


Jaro

 

Water lines # 3 and # 4, starting from the baseline, should not have straight runs, in my opinion.

 

O.K. I shall look into it, many thanks.
Jaro

 

Your design reminds me of a boat I've seen on the woodenboat forum, designed by Bolger. Also a narrow squarish efficient boat, 31 foot in plywood. There is a 166 (!) page long build thread. I've linked to a page that has some pictures of the finished boat.

http://forum.woodenboat.com/showthread.php?80153-Just-fore-the-fun-of-it-)/page133

 

Many thanks, that is lots of reading. I have dropped the transom area since and the resistance figures go down.

 

If you want propulsive efficiency with a displacement boat then you should maximize waterline length. That means vertical bow and vertical transom. Very little overhang.

I have no experience with steel constructions, but intuitively I would say that vertical bow and transom should make things easier.

If you have access to real cheap steel construction and is not limited by a certain length of mooring then go for a longer hull. As long as you can afford. You can always leave part of the interior empty for a few years if your budget can't cover everything now.

In a few years you will probably wish your boat was 42'-45'..... not 36' And the extra waterline length give you more speed potential, even if you don't intend to use it initially.

 

Jaro, I checked the water lines aft and, contrary to what I said in the post # 2 and # 4, they may be correct. My apologies.

 

Well I m playing with it more, I might try to make transom vertical and see how it looks.

 

Resistance curve now looks like this. Am I doing something wrong or is this absurdly low?

http://hawkwind.sweb.cz/Resistance curve 4182382484331.jpg

When I did my school, that was more than 20 years ago, tools like this werent availble and I was ment to be engine specialist. We skimmed hydrodynamics, not that I remember anything much anymore. .)

Jaro

 

Now transom vertical and the chine too more so.

 

Shows this now:



Jaro

 

I can not say that some shapes are better or worse than others because it depends mainly on what you want to do with your boat, but you could try something similar to FIG. Thus, the outflow of water from the stern be much smoother. Although other aspects, such as the wet surface increases. But it is to play and compare results.

 

I see what you mean.

Jaro