designing a fast rowboat

[terhohalme]

Finnish rowboat

Attached a new rowboat of my design for this summer competitions in Finland.

Terho

 

[Raggi_Thor]

Wow, nice, it looks very light and fast!

 

[mike1]

Terhohalme,
Looks interresting, tel us more length and for what racing? Or is this still secret
Mike H

 

[terhohalme]

Boat length is just below 6.5 m and it is designed for this rule (small boats):

http://www.suursoudut.net/eng/default.asp

These boats have a seiries of long range rowing competitions 10, 30 and 60 km, and short range of 2 km.

 

[nordvindcrew]

catchng up

RE: Scilly gigs, I know Hillary Moll as we row in many races where the Saquish womens gig team competes, donated a bit of $ to finance their trip. They are serious about their rowing! Clint, the distance from thwart to oarlocks is a function of beam. Picture a 5' beam and oarlocks 10" behind the thwart, your effective length of pull is very bad. Increase the distance of thwart to oarlock and the catch moves aft to a better point and the length of your pull finishes much further aft resulting in a much better arc at the blade tip. PLEASE, don't be taken in by a one size fits all formula to place your oarlocks. Clamp an oarlock to the gunnel and sit on the thwart and analyze your pull, it wants to be evenly distributed between catch and release. I find it uncomfortable if I have to bend too far forward to get my catch, and like being able to hang on the oars at the release to help with the final snap and to help pull up for the next catch Perhaps, for a mad windmill stroke with an almost insane cadence you could place the oarlocks at 10" and row that way, but, I can't keep up a pace like that for long with short quick pulls of only 4 or 5' feet at the oar tips. I've never measured it, but I think our oar tips cover at least 10' on a pull with a relatively slow powerfull cadence. Pericles, can the spandex , get an oar on gunnel boat and row just for the enjoyment of being on the water. Hell, Build A Gloucester Gull Rowing dory and have a ball! Row Hard, No Excuses! We could all take a serious lesson fron Teriholmes' boat and the races they do. very serious business over there. Best to all, Jeff

 

[sailing canoe]

lofting question

HI all ,Clinton somewhere I saw that you lofted you boat at 1/4 scale. What did you use as a batten to make the tight turns. I just ripped a 3/16 lexan batten but it still too stiff at this scale. I have some enlarged photo copies too make some pear shaped curves. Chapelle calls these "Dixon Kemp curves , but I got my original copy from a book that pre dates Dixon (I think).

 

[sailing canoe]

Opps hit some thing wrong - any way I look foreword too finding out what magic materials you used. Then there is always 20ft full sized battens. On the pear shapes I have only got as far as gluing the photo copies on MDF. Back to work - thanks Nick

 

[Clinton B Chase]

I have not yet lofted my new drawing, the sailing dinghy. When I do I plan to do it to 1/4 scale and make a variety of spruce, fir or E. White pine battens as well as have handy the plastic splines designed foe use with the drafting ducks (the spline with the notch in it for the hook on the duck). I will line off for 5-7 strakes on this lofting, convert the table of offsets to heights and widths to the chines and then full size loft to these offsets to get my sections for the molds. I have not seen or heard of anyone using this specific approach so I plan to market it and sell it for millions

In the meantime, I plan to float the faering next week or week after, get my CF, make thwarts and get the thing in the water for some serious late summer rowing. Can't wait. Nervous already!

Best<
Clint

 

[sailing canoe]

lofting

Hi Clinton Yes I tried the typical plastic splines but they would not bend tight enough at 1/4 scale. Possibly because the canoe sections are rather small. I tried using French curves but as Chapelle says they were not that satisfactory. So I have now made a set of the Dixon Kemp curves. There is a picture in Chapelle's Yacht Designing and Planning on page 13 and he talks about using them on page 18. They sure look cool. If there is interest I could attach a large tracing of the set I made to a post. It would be a lot cleaner than doing your own enlargements at Kinko's -Nick
Post us all a picture of it floating - and no worries

 

[sailing canoe]

norvindcrew?

Hows the boat doing . Seems like we havent had an update recently? Hope things are going well. Clint - rereading the recent Wooden Boat article on 1/4 scale drafting I noticed the auther recomended strips of gasget material, More bendy I guess - Nick

 

[DickT]

Rowboat

I've been following this thread for a while. Here's a pic of my 17' boat.

 

[charmc]

Very nice, Dick.

Can/will you share any details on construction and performance?

Since you've been following the thread, you know we're all suckers for the details.

 

[DickT]

It's mostly epoxy edge glued 5/16 x 2 5/16 pine that was destined to be brush handle stock.Bottom board is 3/4". The only fiberglass cloth is on the bottom up to the waterline. It weighs about 85 lbs. I started roughly from Herreshoff's lines drawing and Norwegian faerings, but winged it as I went. I think the prismatic coefficient is a little too fine for sustained hard pulling. I starts to develop transverse waves over 5mph. I'm still messing with the setup. I like sitting 2-3" off the floor, but the oars hit just over my sternum.

 

[charmc]

5 mph for 17' LOA is not bad. Earlier in the thread someone was describing flip out oarlocks, which allowed the oarlocks to sit 3-4" outboard of the gunwales. Makes rowing a narrow boat a lot easier.

I like the overall look. You must be a good winger.

 

[Clinton B Chase]

I think the prismatic coefficient is a little too fine for sustained hard pulling. sternum.

For a boat made to race at top speeds, I guess this is a problem. My faering is hopefully going to go 5 but only when I want to for fun...what I wish to do with the boat is row all day...days on end actually. This summer will be the test...we shall see. Seems like a very expensive, time consuming experiment. I think it will all work out, but I am still anxious to find out.

I like the look of your boat, Dick!

Clint