Displacement speed HP requirements for 20' flat bottom skiff

http://www.pssurvival.com/PS/Boats/The_Dory-Boat_Book_1978.pdf

 

only to who can understand:
in small boats is not desirable wing submerged, just sacrifice a little power in negative trim
but the bow must be piercing

 

WindRaf, I have not searched any time a bad response. I think I have expressed myself correctly. Simply, in my opinion, your design is seriously flawed and so I ask you to tell me your experiences with this boat.
An experienced eye can be wrong. As I do not have that kind of eyes I've done some calculations with your design and have calculated than the center of buoyancy, for flotation that you have drawn, will be at about 7.44 ' from aft end. That, in my opinion, can not be described as "very backward".

 

TRANSL,
you're bored me.
stop.

 

WindRaf (I'm TANSL), why the discrepancy bores you ?. Are you not able to talk ?. If I have no reason, you say and go. "You're looking for a bad response".
Your lack of explanation makes me think that, maybe, I am right.

 

transl,
why do not you design a model in response to the thread?

 

Why ?. I do not think YotaTruck neeeds you or me to design a model. He is showing the boat he designed, nothing more. YotaTruck, in his first post, said: "can someone give me a real world check on my math and design?"

 

Tansl, Windraf has some of the communications issues, you've experienced over the years and I'll add, his design skills are rudimentary at best. His design package is freeware, which should give you a clue about his investment in design software. Simply put, the design Windraf has posted has nearly as many issues as the OP's sketch, though it does have some rocker (I'd love to see the wave train on that thing ). Doing battle with Windraf will result in nothing but frustration, as he really doesn't have a clue, though thinks he might, which is the worst type of contributor here.

Back to the subject at hand, the OP needs to make some decisions, so he can refine his search for a suitable design.

 

this is my first post in this thread:

...Your design is not adapt to the performance you want.
Here an EXAMPLE, my design, what is exatly you nedd.
Is not 20 ft, and is not designed for to be built in plywood, but this is the geometry.
Same disign, but in plywood and 20 ft long will have 7 knots with an engine 7 hp, and 12-15 knots with two engins 7 hp.

An EXAMPLE.

Maybe i have comuncation problems, but someone here don't know how to read english.


About my example:
I have in my archive a Uffa Fox design, 1970, 25 ft, project and pic of the boat in the sea.
Same concept.
Uffa Fox 1970.
Here, the MODERN semi displacement like my EXAMPLE, are built from 20 years, yacht medium and also big.
This kind of yachts in this moment moment are in great demand.
In this moment are build also tugs, and ships 300 meters long in this geometry.

Comunication problem? no, nautical culture problem.

 

ah, and about the wing submerged, you have not understood the essential: put the wing submerged with a puffy bow is nonsense.


'His design package is Freewar''
so? of course for quick drawings, I use what is simple and speed,.
or do you think that I would put HERE projects forty thousand euro?

the package freewar is your mind

 

Hi PAR, I understand everything you say and you are quite right. As always, I believe that giving bad advice can be harmful and to tell someone "leave your design and adopt mine" at least you should give a better design. So I try to make clear whether any design seems bad, explaining why. Free software can be used but what is not free is the analysis of the results we get from the software. Just to mention the most obvious thing I've seen, the curve of areas of frames that presents WindRaf has positive values on the left end, where there is no submerged hull. It is therefore a wrong curve. From there, what else can I say ?.
In short, speaking for YotaTruck, do not listen to what he says WidRaf because it is unreliable, that is, because he is wrong.
I do not know if anyone will think I've broken this thread but I thought it necessary to say that any of the proposed solutions are wrong.

 

Doesn't look too flash at the stern end, either (curve of areas) !

 

According to the curve of areas that WindRaf has shown us, the center of buoyancy is located 2390 mm from the aft end, ie LOA / 2. That can not be considered as "very backward", as a "trained eye" can easily deduce (see post # 11).
I'm afraid WindRaf is confusing the LCF with the LCB and the blame for this is not in the free software.

 

never see a sail boat with spoiler?
is it wrong?

 

I'm asking myself if some 'designer' here are typing from Borneo