New member here interested in rowboats

Gee, 4mph over 2 hours, thats pretty good

in terms of surface area, the semi-circle is best, trouble is that it is not stable, so people tend to flat it out, sort of like a flat ellipse, then you can add a slight vee section as this adds lateral resistance and improves tracking because you have a kind of keel

a fine bow is good for going through waves, if it was not for waves, then in theory a teardop shape is best, rounded bow, tapered stern

if bow is too fine it can cut through large waves, but not have enough reserve buoyancy to lift up, thus water can get into the boat. Also generally you want the forward rower to have good rowlock to rowlock distance, hence rowboats sometimes flare out a lot at the bow in order to give the front rower reasonable distance to set their oars.

 

Troy all these semi-rowing shells are great in protected waters and probably all attain the same approx. speed per given length. Joel's with it's floatation chambers certainly would be a better rought water boat than most. Rough water determined of course by the body of water in reference. Rough water on the average lake woud be an average day on the ocean. In reference to Joel's, it reminds me of a cut down Pea Pod which at full size is a close rival to the dory for sea keeping abilities. It's the old adage of choosing the right tool for the job. If your rowing area includes open ocean work, the old faithful dory style while heavier and slower is easier to handle, dryer and certainly safer.
P.S. Troy, CRS must have now gone North American wide as the same symptoms are showing up here

 

I'd say the Bangor Packet's better seaworthiness isn't just due to its built-in flotation; there's more to it than that. But of course 'seaworthiness' is a relative term, and you're right: if you habitually row in rough water and want to keep the dry side up and comparatively dry, a dory or a peapod is going to look a lot better to you.

 

PA, I think your'e say'in a combination of round and V. Or perhaps flattish (arch ?) w "small radius hard chines". I think the sharp chines and resulting turbulence of flat bottoms ruin an otherwise excellent form. I would think the V would push water aside (as all boats do) but not as far aside saving energy and causing less resistance. Just a seat of the pants thought/theory.

 

Yes Troy argree 100% it has to do with more than the built in floatation. I think that model as adverised was developed from the origional hull for rougher water work. The origional hull in itself is a very sleek piece of rowing equiptment and no doubt has some pea pod influence. Once i complete my present build a pea pod will be my next project. How is your build coming ---

 

There is no flotation in this boat, except for the fact that it is wood. But some of that wood (floorboards and oarlock mounts) is sinker cypress, so that will reduce the bouancy.

Do you think I need to put styrofoam blocks under the fixed seats? That would really mess up the good looks of the boat.
.

 

I thought flotation was the Law ?

underseat billet foam blocks work fine. Ive always used pour foam in the forpeake and sternpeak of my rowboats

I believe small craft can also use inflatable bladders...perhaps double check

 

For commercially built boats, yes, flotation is the law. For custom builds and restores, I don't think the flotation requirement law covers that.

 

That isn't going to happen on my rowboat. It would ruin the good looks.
And suffocate the mermaid.
This is a fast "show" boat, not a row boat!

 

It isn't, unless you're good at taking the long view....

Three weeks ago I was patting myself on the back, because I was mostly finished with the shop where i was going to start building the hull. Unfortunately, due to overtime and union business commitments I haven't been home since.

I was looking forward to my 'long change,' when I get off on a Monday morning and don't come back to work until the following Tuesday morning. I was going to use the time to add shelving and storage to the shop, and start moving tools into it. But this morning when I was getting off work, my relief asked if I would cover his night shifts the last four days of my long change. I'm not financially or emotionally in a position to turn down four 12-hour shifts of overtime, so I'll only have a couple of days at best to get the shop ready to go.

 

That's terrible. How can she be a proper guardian, if she can't see where you're going? Sheesh.... you might as well put her to rowing, and get some use out of her.

 

Troy I hate to be the bearer of bad news but it doesn't get any better with time. At 68yrs. old while i've shut down my construction buisness last year, i still have to work at something to make ends meet and take a holiday once every two to three years. Right now i've got two part time project management (construction) jobs, Preping the B&B for opening this season, Installing all new siding on the house and fignting for time to get at the build. Oh plus rebuilding my old Jeep in prep for my Moose Hunt in NFLD this fall. Stubborness is the only way to prevail.
Speaking of keeping ones head above water, floatation is indeed a good idea. In cold water more important than a lifejacket as far as i'm concerned. If you get swamped, properly located floatation will give you enough freeboard to allow bailing, not so without floatation even in a wooden hull.

 

I don't know where you got that theory, unless you're thinking of the medieval "cod's head and mackerel tail" theory, which hasn't beeen taken seriously since at least the mid 19th century.

Keep going. You've only thought it through halfway.

Your boat is going to have a given displacement and length, which means (all else being equal) that regardless of changes in section shape the cross section area will have to stay the same.

When you consider that, it should be clear that if you push the water less somewhere, you will have to push it more somewhere else.

 

NoEye wrote;
"you will have to push it more somewhere else."
Yes ...... like down. The deeper the hull the further down it will push water.
With the flat bottom the water is hardly pushed down at all but the chine turbulence is not good. With a 3" radius on the chine I would think the flat bottom would be fast. But isn't wetted surface king at this speed?

The reason the radius on the chine of a flat bottomed boat is not seen is obvious re the ramifications of constructing same. A 1 1/2" radius is not too difficult w an over sized chine log but 3" ??

 

General opinion from reading many books is as follows. Maximum underwater cross sectional area should be somewhere between 50% and 55% of the waterline length. The section should be semicircular as this provides minimum wetted area with maximum volume eg rowing shells, but this has problems in blending at ends so elliptical is good, then maximise Cp and have a smooth sectional area curve. Put centre of bouyancy and centre floatation at max area section and you will be very close. Then there is the above water concerns of smooth water use? rough water use? windage? length? cargo? passengers? etc eg bow shape is a huge discussion. There are many many variables to sort. Peter s