Thread: Herreshoff Rowboat

Not sure if that powderhorn sheer is just the angle the photo is taken from. Looks ok here.



Interestingly Michalak also redrew and simplified Culler Otter.





http://www.duckworksbbs.com/plans/jim/batto/index.htm



"Slick as snot"



Brian

Originally Posted by keyhavenpotter

Wow, thanks MIK. Pretty extreme. Very striking though.

Clint, just for comparison, is there any chance of posting some lines of the Culler Otter. In the pics on the WBF thread she looks to have a much wider flat keel plank, so I must have gotten the wrong impression.

Brian

A pleasure Brian,

Modelling whole boats takes a lot of time ... even more than designing from scratch. Main problem is the mathematical method the computer uses often is not compatible with the rectilinear data (offsets are heights and widths off a grid) used in boat plans.

Huge job to get something similar.

MIK

A Us builder offers plans for a boat based on herreshoff's design



and interestingly a shorter version to make her lighter to car top at 65 lbs



Athey

Brian

About 10 years ago, longer in fact it was as a teenager i built a slightly shortened to 15 feet ultralight version of the unrevised herreshoff design as in Gardners book. It was great in that at around 23kg it could be handled and cartopped ashore just alone.

It was however, as noted here squirrily, partly i guess due to its lightness and in part due to the fact that in shortenning it by re-spacing the molds i didnt reduce the rocker at all so for its lenght it had slightly more rocker.

I found that at 15 feet it was masnagable ashore which ws a key reqirement and sweet to row, apart from the directional stability issue which could be dealt with by rowing technique.

Unfortunately the last i heard was it was decorating some clubs roof, after being hold when it blew off the garage roof in a southerly. Im trying to track it down. It was my first serious boatbuilding project and i hardly used it.

It was almost frameless apart from 3 around midships, and had a spreader both fore and aft. It was JUUUUST stiff enough in 4 and 6mm ply.

Barbera Bitchface

Nice Story Barbera B!

MIK

The Herreshoff rowboat can tolerate several modifications to address a few common issues with the type. John Gardener's changes address some of them, but since his revisions in 1980, material choices, building methods and shape efficiency have "evolved" a bit and more can be done.

In the early 90's I was asked if the boat, which in it's traditional stock form, is about 100 pounds (45 kilo) dry and in the 125 to 130 pound range (57 - 59 kilo) once all soaked up, could be made lighter, faster and more "user friendly".

She was considered light for the era, but necessitated dainty ribs on close centers, an inwale, gaurd, heavy (relatively) keel plank, and stems. All of these things are now extraneous with modern building techniques and materials.

Her fidgety nature, underway with a light load is typical of a fast pulling craft, but some things could be done to firm her up, though most of these things would also slow her down. After a weight study, I found I could build one at about 55 pounds, with all the changes I envisioned. She wouldn't be any more durable or stiff and abuse will likely damage her relatively easily, but this would be true of any lightly built craft. What she would be is slightly faster, a lot lighter, about as maneuverable and have less internal volume.

It's imposable to get plywood planking stiff enough to work, yet light enough to consider, so I tossed this idea out right away, going instead with molded white spruce planking, using veneers with a slight cant, per layer (about 12 degrees). these planks where 3 layers each and about 2/3's the weight of plywood, though good 1/4" (6 mm) Okoume was less this percentage, not stiff enough for it's weight. Planks molded full length, then trimmed to shape.

Gardener's entry changes are a step in the right direction, but more attention to the Froude number the craft operates in, suggested additional changes to the entry. As a result the lower waterlines on the model were reshaped to remove most of the concavity, in compliance and respect to the her wave train. Her exit was fine and no changes made, though some improvement could be made there, not enough to warrant changes. The weight reduction as a result of building and material choices necessitate a narrower keel plank, understandably. This makes here easier to plank up than the Gardener version, which is slightly more difficult than the Herreshoff model, though both are easy boats to plank.

The bottom plank is a 5 layer veneer laminate of Douglas fir, though Port Orford could be used too. Because the boat is glued lap, rather the clenched or riveted, the laps don't need to be quite as big, though making reasonably precise bevels will keep the epoxy weight down, which is important. Built upside down over station molds, she can be built with no frames, just thwarts, no stems, just fillets and a combination rail/cap "T" rather then inwale and rub, all of which save a huge amount of weight. She's a one handed boat for a young man. She still needs breast hooks at each end, but other then this a fine, slightly narrower, slighter faster, easier to build, still dainty pulling boat of spectacular grace underway. She'll still be fidgety with a light load, but if you want fast and easy to propel, you have to accept some discomfort.

PAR,

I found that Green Machine, Gardner's version available to row at Mystic, was very fast, but the stern would suddenly begin to fall off with no warning. Being skegless, much like a trad. dory, the trim must be slightly stern down so the aft portion of the bottom plank/bottom joint produces the lateral resistance like a skeg, thus helping the boat track.

Myron Arms, recognizing this major issue, built his rowboat with a windsurfer skeg attached. When I rowed his, I was very, very pleased. Fast and excellent tracking.

Keeping the hull finer aft like you did was a good call, because the boat needs to settle into the water aft to get the tracking...I imagine the narrower plank bottom helps too.

I am very intrigued by your planking method, would love to see pics, esp. because W. Spruce is a favorite of mine!

Cheers,
Clint

The redo of the Herreshoff was a design exercise for some students that were very enamored with the boat and Gardener's version. One person said they were doing her up, but I never heard from them again (typical). The discussion surrounded potential changes to the design, but she was considered perfect as she was, at which point I had no choice but to jump all over them. Every design can tolerate some "adjustments" to both shape and build, particularly as they age (the plans) and newer techniques, materials and methods become available.

Veneered planking can be a good and bad thing. The good parts are you can orient the panel stiffness the way you want and make "dog legged" lengths of stock to keep the grain running the way you like. It's also a fairly economical use of materials as there's less waste then cutting 4x8 sheets of plywood, where you know you'll have lots of elongated triangles that will be useless for anything else. On the down side is the lamination process. On several occasions I've laminated veneers or long lengths of plywood. Each time I've built a long table to do the laminate on. This process is time consuming, compared to just cutting a panel shape once, like with solid or plywood planking. If you can bag or have good laminating skills, it's a good approach, particularly if you can get reasonably priced veneers.

One thing I also have done is cut and joined plywood panels, fitted to shape, then applied a veneer over them for a bright hull. Personally, I think there's little worse, then seeing the wild grain of rotary cut plywood under varnish, but some nice vertical grain veneers glued over it and no one knows the wiser.