Hullform development article

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SteveC
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Hullform development article

Post by SteveC » Wed Dec 01, 2010 10:29 am

I have added a new article (or rather quite an old on actually) which I acquired from a dubious source (Colin). With acknowledgement to the author Bill Beaver, I believe (please can someone confirm), it's a very interesting insight into hull shape development over the years with an analysis of what shapes have come and gone and how they performed.

The link to the article is http://www.intcanoe.org.uk/index.php?op ... &Itemid=70 or look under /Resource Centre/Design.
Steve Clarke (UK)
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jimc
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Re: Hullform development article

Post by jimc » Wed Dec 01, 2010 11:53 am

It would be interesting, of course, to do full size tow tests on the various shapes we have now. From the modelling I've done so far the Morrison is the winner on wetted area, but Chris Maas first boat is very close and has a much higher Cp.
FWIW my experimental Nethercott stern theoretically increases both CP and wetted area, but my gut feeling is that the biggest win areas on the Nethercott shape are in the under mast area and above the waterline forward of that. At speed the Nethercott is incredibly noisy in those areas if you are used to modern skiff type hulls, and the only new boat I've sailed so far, Tin Teardrop, was much quieter. Of course once you change those things significantly though everything else has to change to match.

SteveC
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Re: Hullform development article

Post by SteveC » Wed Dec 01, 2010 12:15 pm

I think that would be a great idea and of course Southampton University would be the place as they have a tank facility and doesn't Uffa Fox's Wake reside there as well as a test model? Frank Bethwaites first HPS book refers to it and shows it in a fairly bad light against the 18' skiff humpless drag curve. It would be nice to bring that up to date and see how the modern shapes perform. Do we have a contact at S'ton Uni?
Steve Clarke (UK)
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Re: Hullform development article

Post by jimc » Wed Dec 01, 2010 12:38 pm

SteveC wrote:I think that would be a great idea and of course Southampton University would be the place as they have a tank facility
We don't really need a tank - a calm day on a reservoir and a setup like Bethwaite's in HPS2 will do nicely. Add to that a GPS and you are pretty much there. Although in an ideal world it would be nice to have a digitally recording strain gauge going to a data logger integrated with the GPS in practice pen and paper would do. Its just a question of towing the boat up to a indicated GPS speed and measuring the load on a spring balance when its stable. I think getting an operational race boat hooked up to the gear in the tank would be a game and a half, whereas a rope attached to the mast and a guy steering the canoe and adjusting trim is fairly easy.

wee mcp
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Re: Hullform development article

Post by wee mcp » Wed Dec 01, 2010 3:54 pm

I have added a new article (or rather quite an old on actually) which I acquired from a dubious source (Colin). With acknowledgement to the author Bill Beaver, I believe (please can someone confirm)

Yep, you're right Steve - Bill Beaver - taken from the US IC Newsletter, "Vol29 No.1 2010" edition

Ian McP
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Re: Hullform development article

Post by wee mcp » Wed Dec 01, 2010 4:13 pm

Uni. tank testing facilities?
Earlier in the year I was involved in a project at Glasgow Uni's test tank and made a tentative suggestion about dragging an IC along the tank. The outcome? ‘Agreement that it would be a valid exercise but basically in this day and age the tank is used mainly to bring in outside money, not teach students. I should imagine Southampton is in a similar position.
So unless we have an insider, like Bill Beaver, I doubt it could happen.
Pity.

Ian
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Craig
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Re: Hullform development article

Post by Craig » Sat Dec 04, 2010 12:49 pm

When I was at Glasgow/Strathclyde, undergraduates were able to use the big Acre Road test tank briefly for their dissertation project (which would easily take a full scale hull) and the department also had a small tank in the city centre witch would probably be able to do testing on 1:3 scale canoe hulls. so if you could get a student interested in doing the project as 4th year project, you might get the work done for free. The difficulty is in producing a usable scale model of the hulls that you want to test. I wish I was still there - it would have made a much more interesting project than mine was!

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Re: Hullform development article

Post by wee mcp » Sat Dec 04, 2010 1:48 pm

Craig,
Yea, it was the big wave/tow tank - http://www.marine.gov.uk/tow_tank_acre_road.htm - that I was talking about, superb facility and a great place to play. :D
The Denny testing tank in Dumbarton, now part if the Scottish Maritime Museum is apparently still in working order, did you have any contact with that as a student? Do you think it could that take a full size IC?

Ian
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Re: Hullform development article

Post by Craig » Sat Dec 04, 2010 4:37 pm

I believe the Denny tank is still working, although I think it is mainly just a visitor attraction rather than a working hydro lab. Dr Sandy Day was the the tank superintendent for Acre Road and the smaller Henry Dire tank that the university uses and it looks like he still is (contacts on http://www.strath.ac.uk/na-me/facilities/cmh/) . He was also the yacht and sailing craft lecturer so would be able to help in terms of turning it into a student project too.

I has anyone done any modeling with the Maxsurf (or similar) sweet of programs? I suspect that there is quite a lot of information that can be drawn from those before you go down the line of full tow tests!

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Re: Hullform development article

Post by Steve Clark » Mon Dec 06, 2010 4:13 pm

Bill Beaver did full scale tests last winter. The results were reported in Canoesletter #29. I think this was distributed to someone in the UK via the Internet. I suggest you contact either Bill, John Kells or Willy Clark to get web worthy copy. Results were not surprising or unanticipated, but actual data is nice to refine the speculation.
SHC
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SteveC
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Re: Hullform development article

Post by SteveC » Mon Dec 06, 2010 5:09 pm

Report is on the UK website http://www.intcanoe.org.uk/index.php?op ... &Itemid=70 or directly from the Home page. It would be good to see a few UK based designs tested in the same way though or at least at a venue and boat on boat testing.

I might as well admit it now...... I'm building a Morrison2 design, slightly tweaked version of Phil Robin's, hence the interest in comparing hull shapes.
Steve Clarke (UK)
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Alistair
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Re: Hullform development article

Post by Alistair » Mon Dec 06, 2010 9:40 pm

Hi Steve
Thats great news, Andy has started my new boat, its one of my own design, but quite different to Monkey. I have started on the other bits, made my tiller the other night and have some laser cut mdf bits coming tomorrow which I hope will make pattern work for my sliding seat and carriage. Also got a whole load of resin and ud to make said bits, but have not tried it out yet as too cold in garage to tempt me out there, but must do some this week. Debated about spars and have decided to make my own.
Again all a bit of an experiment but I hope to end up with a better finished boat than monkey. Monkey is for sale or hire for the worlds, but I am in no hurry as I need to take measurements from her.
Alistair

SteveC
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Re: Hullform development article

Post by SteveC » Tue Dec 07, 2010 10:03 am

It will be great to compare notes and also with Colin and John on progress. Intention is make the parts from the AC interchangeable and avoid a lot of work on the accessories.

I'm currently building a male mould/plug which is almost finished and hoping the temperature goes up in the next few weeks to start laminating, currently just getting glue to go off is a problem requiring blankets and electric heaters. I think I will build a box aroumd the plug to act as an oven.
Steve Clarke (UK)
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GBR242
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Re: Hullform development article

Post by GBR242 » Tue Dec 07, 2010 9:08 pm

OK, so getting a 'big' towing tank may be hard.....

but what about a small one ;-)


http://www.lminteractive.co.uk/stuffforsale.html

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SteveC
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Re: Hullform development article

Post by SteveC » Wed Dec 08, 2010 3:33 pm

It's a bit tiddly don't you think! :(

There was a debate elsewhere about using models. My view is that the properties of water on a small scale model can't be properly represented and therefore doesn't represent real wetted area and therefore not very meaningful.

Jim's suggestion is probably the most practial.
Steve Clarke (UK)
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