designing a fast rowboat

Yes the boatbuilders perennial problem, not enough clamps! I prefer the F clamps but only buy good quality ones as the cheap ones slip. DIN 5117 is the German standard for F clamps and any made to it should be a lifetime use job.
Nice job, she looks very sound.

 

Sweet looking boat, Jon! I'm building a longer version of something a bit similar and had some (actually a lot of) questions. Is it stitch and glue, 4mm planks? Are the bulkheads 4mm too? Are you going with fabric over the bow and stern chambers? How thick/stiff is the bottom board? I put in similar ribs (9mm Joubert) every 24" but want to lose weight am wondering about trimming them down -- does the one rib seem like enough?
Best Regards,
Tallman

 

Bulkheads are 4 mm and they seem to be quite stiff. Shouldn't be a problem. Decks will be aircraft dacron, again to save weight. Bottom is 6 mm. There is only one substantial rib at station closest to where single station oarlocks will be. I don't know if this will be enough. We'll see how much flex there is once I finish installing the inwales. I don't know what the final weight will be but this one is considerably lighter that the last one and that one is about 100 lbs.
My part time retirement job is demanding more of my time so progress on this puppy may slow a bit, not that it wasn't slow already. Should be ready for Spring.

Jon

 

Almost Done....

The boat is coming together. Just have to heat shrink the dacron decks and apply the final coats of paint and varnish. The final coats will be done after the boat goes down the stairs and out the window, in case there is any scraping. My shop is the attic of the garage and unlike Pete Culler I did not provide an easy way to get them out.
I'll weigh it this weekend to see how light it turned out.
Hopefully there is a picture here.

All in all a nice way to kick off the retirement!!

Jon

 

wow, looking good, bet your'e starting to get excited,,new season and a new boat.
have fun
Mike

 

I've been looking at the beam max of rowboats,
Gartside runs to about 56 inches for both Bob and his Coastal rowboat, this seems to be the starting point for most rowing boats, that's shear beam not thole pin.
Herreshof / Gardner is 44 inches thole pins extra, and Guide boats about 40 inches,
That's quite variation,
So why the greater beam and What exactly is the advantage of a greater beam??

 

longer oars, you want roughly a 2/3 rato, the length outboard of the pivot to the length of the oar. wider beam means the 1/3 inboard can be longer. longer oars have an advantage up to a certain magic length. that length is debatable, each person having their own theories and ideas. I like 9+ footers for boats like the stretched light dory.

 

Beam is 42". Spread for oarlocks is 46". I use oars that are 9' and I overlap my hands. For me, it feels comfortable.
Andy Steever wrote a book around 1985 on oars and techniques of fixed seat rowing. It is very technical, a very involved study and a labor of love on his part. It's worth trying to read if you have a passion for fixed seat rowing. I believe it is still available from Mystic Seaport.

Jon

 

I design my rowboats around the oarlock spread that I like to use. Using the ratio 7/18 for inboard to outboard, and then factoring in what sort of hand overlap I like/want, you can arrive at a beam. I love using folding outriggers to get me out to 9-9 1/2'...that is my favorite length. No less than 8 1/2' for my rowing style.

I'd second the Andy Steever book. He has a very complicated oar length formula, but it is only for the very studied oarmakers/rowers.

One thing about Paul's coastal rowboats is the topside flare is quite a lot (in order to keep wl beam down and max beam up) and I am super curious what that hull form feels like in a lumpy wavy sea state.

 

Hi, I do have a copy of Andy Steever's book, , your right,very much worth a read , as well as "A Text book of oarsmanship " by Gilbert Bourne, first published in 1925,, mostly about sliding seat , but it really applies to both fixed as well.
There are chapters on physiology that are wgems and a discussion on the weight balance and design of oars,, much the same as Andy steever. In 1910 he was p off with the oars and togther with a friend measured all the oars at oxford, the had some especially made for the eights the improvement in the crew was such that they could rate 46 for 2 mins. The improvement in the oxford new college crew was so great that they went on to set numerous records, and were invited to represent England in the 1912 olympics..
Bourne puts all this down to the oars,, so Steevers book (which takes the design of oars further) is well worth a read.

 

When we were doing the Oarmaster Trials in the 80's Andy Steever got in touch with me and we would provide him with the data we were collecting and he would offer lengthy comments about the oars being used and suggestions to improve. The man had a real passion for the stuff. I never got to meet him in person, wish I had.
Andre D'Barteleban has all the stuff we collected from the Oarmaster Trials, I sent him everything about 10 years ago. There isn't much to learn from it, our efforts were very crude. Everyone has progressed beyond the simple stuff we were fooling with then.

Jon

 

Hi all, over the years there seems to have been quite a bit of "research" done, but at the end of the day its the tinkerer that seems to make the break through's, practical workouts seem to produce real results,,
we also should bear in mind that its fun we're looking for, well as you approach the 70's that is.
Right now the sliding seat dudes have Valery Kleshnev and his Biorow, with huge amounts of technical data and resurch,
however at the end of the day its the athlete that counts, and most are there for the fun..
Here in Cape Town we have just had a cycle race of about 110 kms, every entrant timed, there were 30,000 participants ( It is a huge day every year) and only about 10 or 15 fighting for podium, the rest were just having fun.
Fun certainly rules.

 

The new boat just weighed in at 74 lbs. Goal achieved. Hope it stays together!!!

Expect to try it out later this week.

Old wherry is for sale if anyone is interested.

Jon

 

Jon , The weight is stunning , to put it into perspective.. FISA the body controlling international sliding seat rowing has an open water section, boat rules for a single minimum weight is 35 kg,, near as dammit to 70 lbs,
Paul Gartside who's is no slouch has Flash boat plans, from tortured ply expected weight, 90 lbs.
Well done, bet It keeps up the tradition of your previous wherry's, that set the standard for safe , fast , home built, open water rowing.
mike

 

Jon, I am interested in the wherry.