Power And Prop Selection For Hard-chine High Speed Planing Crafts

[yades]

After having performed an extensive research on the Internet and viewed forums (even the present one under boat design topic), sites and all relevant literature appearing on the web I came to the conclusion that there is a great deal of information available however not comprehensive enough so as to cover systematically and concurrently the evaluation of a propulsion system of a hard chine planing hull in all principal aspects which are Resistance-Power-Propeller matching.

PC, related spreadsheet and dedicated software has made this evaluation easier enough to be worked out, however, practical empirical or semi-empirical methods available, together with a methodical approach, seem to be (at least from what has been gathered from the web….) not commonly accessible and far from embracing the subject thoroughly.

As with regard to Hull Drag and Thrust evaluation I found Dingo Tweedie effort with his spreadsheet remarkable and extremely useful so as the one from Hawaii Marine Company I must say. However, it would be of further and more valuable assistance to my opinion gather some more interesting informations concerning losses involved in power generation and in power transmission and some other supporting procedures in prop calculations either using the Bp-δ charts or Kt-Kq charts from Wageningen Type B prop curves.
All this, at the moment, seem to be scuttered over various papers and books, undoubtedly of extremely valuable assistance, however specific on each distinct subject. Resistance and Propeller Dimensioning are, more or less, treated as ....two distinct subjects !!…….
Fair enough !…..

This thread will endeavour to provide an opportunity to cover the basic elements/requirements on the subject in a more analytical approach partly with infos/supports readily available and partly based on supplementary practical and semi empirical elements generally available but valuable in providing a complete sequence of events on the above mentioned assessment procedure. All based on first principle of naval architecture and currently available informations which must be familiar to a general power boat enthusiast and/or naval architect/yacht designer/marine engineer.

I believe a major technical contribution could be offered in that respect on this forum via comments, technical support, reference papers, links, suggestions and specific but useful technical data, which could herewith been added so as to enhance anybody knowledge on the above mentioned subject.

The first step which I will shortly add hereinafter will be “PART 1”, outlining the main parameters and ratios involved in hull resistance calculation and thrust.
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the view herewith expressed is that of the author and is reputed being true to the extend of his knowledge. Indeed if any adverse opinion is deemed to be outlined and argumented It should be substantiated in practice for further & better understanding. Moreover, all information hereby provided in terms of templates, graphs, technical documentations, empirical or semi-empirical formulae, spreadsheets and so an so forth are to be considered on “as is “ basis without warranty of any kind, either expressed or implied and the user is required to verify that all aspects have been covered correctly for the purpose intended.
Nevertheless, every effort is being made hereinafter so as to assure accuracy and validity of all technical informations provided.

Yades

[Willallison]

1st up let me say, what a shame it is that 'we' have come to the letigiuos point that Yades feels it necessary to include a disclaimer at the end of his post. I understand his caution, of course, but wow.... we really need to take a look at ourselves....

Now, onto the question at hand

There is also a very thorough spreadsheet in our 'library', kindly uploaded by Casper, which goes some way to addressing your observation:

http://www.boatdesign.net/forums/dow...?do=file&id=26

I also think that Gerr does a good job of simplifying the black art of prepellor selection in his Propellor Handbook

Great thread Yades, I look fwd to its progression

[yades]

Originally Posted by Willallison

1st up let me say, what a shame it is that 'we' have come to the letigiuos point that Yades feels it necessary to include a disclaimer at the end of his post. I understand his caution, of course, but wow.... we really need to take a look at ourselves....

Now, onto the question at hand

There is also a very thorough spreadsheet in our 'library', kindly uploaded by Casper, which goes some way to addressing your observation:

http://www.boatdesign.net/forums/dow...?do=file&id=26

I also think that Gerr does a good job of simplifying the black art of prepellor selection in his Propellor Handbook

Great thread Yades, I look fwd to its progression

The spreadsheet you're referring to I believe (correct me if I'm wrong) being that of Hawaii Marine Company .....as stated in my post ...extremely helpful......still ....not complete as intended.......
Dave Gerr is part of that extremely useful literature which I mentioned previously ...but...still.....very keen reference on "Propeller Design" on the specific.!...And again.......why buying a book to gather infos .....we should start having something perhaps more ......complete......also on this forum ......a sort of an ..ALL INCLUSIVE....general reference paper on the subject...or...... a FAQ.......generally available............maybe too pretentious.. ......but still worth a try!

Any more comments.........always welcomed.!!..

Yades

[Bad_Trim]

Or... you could always hire a proffesional

[yades]

Originally Posted by Bad_Trim

Or... you could always hire a proffesional

Right though...!........first ...If I may......I Would rather write ..."proffesional" ........in this way......"professional" ....(forgive me but dont you think is better?!.. ..) ..secondly I'd assume being not in the spirit of a forum suggesting to ......"hire a professional" .....wouldn't you ? ..I'm sure that's was a joke !......

Yades

[yades]

Originally Posted by yades

Right though...!........first ...If I may......I Would rather write ..."proffesional" ........in this way......"professional" ....(forgive me but dont you think is better?!.. ..) ..secondly I'd assume being not in the spirit of a forum suggesting to ......"hire a professional" .....wouldn't you ? ..I'm sure that's was a joke !......

Yades

P.S. I rather say...."that was a joke"....right?...

[yades]

Here is the compendium dealing with the Bear Hull Resistance (Section A) ...Nothing new ..really...however useful to find all relevant matters gathered in few pages....will continue further with Section B as stated at the end of enclosed doc.

Any comments ...speculations...and so and so forth ..v.m. appreciated.

Trust ...being useful to many interested fellows.....

Cheers!

YADES

[Willallison]

I've not yet had a chance to go thru it in any detail yet, but on 1st glance thru, I must congratulate you on a very well presented, professional looking paper. Nice work!

[yades]

Originally Posted by Willallison

I've not yet had a chance to go thru it in any detail yet, but on 1st glance thru, I must congratulate you on a very well presented, professional looking paper. Nice work!

V. M. appreciated ......any keen comments on the subject....will help further ....

Till the next one.....

Rgds

YADES

[Jango]

Here's a very useful Prop Calculator. It works for Me

http://www.castlemarine.co.uk/pitch.htm

Jango