How to design the seating for a white water dory

Note: As of 15_Jun_2021. This page and this boat (the Whale Rider) are still in development. They will evolve as the season progresses. There are no online plans or blueprints for the Whale Rider yet.

How do you design a Grand Canyon Dory? The ground rule requirements are to build the most nimble, most stable boat approximately 17' feet long that can carry four passengers and one rower--which is the way white water outfitters typically use these boats. An additional goal will be to somehow make it possible for the same boat to be used by do-it-yourself river runners who do not have a support raft coming up behind who, with a minor adjustment to the seating arrangements could then use the same hull to carry only two passengers rather than four, so there would now be room for food, cooler, tents cots and sleeping bags. Plus groover.

Several 15' foot Montana Riverboats Honky Dories have made it down the Grand Canyon this way. So it's certainly possible to make a dory two and a half feet longer that would do the same. The question is how best to do it.

A little Nortwest Fishing Dory History

The 15x48

The traditional 15x48 McKenzie boats (including the related but slightly flatter Rogue River style boats) typically placed two passengers side by side slightly forward of the middle with the rower approximately 40" inches back from the passenger seat. That seating arrangement squeezes the payload as close to the middle of the boat as possible. Dories with most of the payload in the middle (rather than pushed out to the ends) are the most stable, most nimble and most responsive boats.

The 17x54

Consumer pressure for bigger boats eventually led to the first 17x54 boats which are typically built with 18' foot side panels, making a boat approximately 17' feet long end to end. This is the same boat as the 15x48 scaled up by a multiplication factor of 1.125.

17x54 boats often (but not always) have a front seat three pasengers wide a little forward of the middle, much like their slightly smaller two seat progenitor, the 15x48. This three-across seating arragnement still keeps the payload as close to the center of the boat as possible.

Even larger

Since the 1990s even larger boats have become common, some (mostly aluminum hull) boats have been built with 20' foot side panels which make a boat with an end-to-end lenth a bit short of 19' feet. Those boats typically have a 60" inch bottom, which once again is the same boat as the original 15x48 McKenzie scaled up proportionately, this time with a 1.25 multiplication factor.

Fly Fishing Boats

In the early 1980s the growing popularity of fly fishing led to drift boats slighly altered from the original Mckenzie so only one passenger was seated up front with one other passenger placed behind the rower. If you want two fly fishermen to fish from the same boat you have to spread them as far apart as possible, else their fly lines become constantly entangled.

The performance of fly fishig boats suffered greatly. Spreading the payload out to the ends of the boat not only made these boats slower to turn it made them significantly more side-to-side tippy as well 1 . That was and still is the price you have to pay for fly fishing.

An interesting side note to the fly fishing story involves bottom profile. The original McKenzie river boats were not meant to carry any weight behind the rower so they didn't need much floatation in the upstream end of the boat. Consequently McKenzies were typically built in an asymmetrical pear-like shape, a bit like a Chinese soup spoon: wider up front and narrower in the upward-curving rear.

Those boats really suffered in fly fishing mode because they didn't have enough buoyancy in the upstream end to hold weight, so in fly fishing mode they drooped down at the rear and reared up in the front--quickly turning a highly-tuned hot rod into a half sunken water mellon.

Fly fishing boats with symmetrical bottoms--that have as much buoyancy in the rear as the front--perform noticeably better. But still not nearly as well as the original McKenzies with their passenger payload centered over the boat's center of gravity..

Decked Grand Canyon Dories

The history of decked Grand Canyon dories revolves mostly around the Jerry Briggs dory, first built in the early 1970s 2 and then a decade or two later with the nifty boats designed and built by the late great Derald Stewart. Those boats are typically made with (approximately) 19' foot side panels and 48" inch bottoms.
/fragments/Whale-Rider/littons
martin littons Briggs Dory

The following is a particularly nice Briggs boat publically published at mountainbuzz.com. Not all Briggs boats face the rear two passengers backward, but this one does.
/fragments/Whale-Rider/mountainbuzz
Mountain Buzz Briggs Dory

The Coconino is an early Derald Stewart boat probably built sometime in the 1990s.
/fragments/Whale-Rider/coconino
coconino.jpg
The Coconino was a double-ender with a gunwale length of 19' feet 2" inches long. If built with a transom at the upsteam end it might have been as much as a foot shorter.

This is a big boat. Like the Briggs it did have a 48" bottom. Carrying capacity was one rower and up to four passengers. As is the case with many but not all Briggs boats, the two passengers behind the rower faced the other way.

The most important part of the Grand Canyon dory story (according to me :=)) is the way they spread the payload out to the ends of the boat, essentially the same way as fly fishing dories. If you take any (any any any) fly fishing dory and put the rear seated passenger side-by-side on the front seat instead, and then shift both seats slightly to the upstream end so the payload is now squeezed over the boat's center of gravity, the performance difference is immense. Passengers spread out to the ends of any dory is not a good idea from a performance perspective. Fly fishermen have to do it. White water river runners do not. And yet they still do.

Designing Outside the Dory

The follwing cell phone photo shows a Montana Riverboats Whale Rider still in development. The Whale Rider has a 66" inch bottom and a gunwale 18' feet 9" inches long. There is no flat spot on this boat. The middle four feet have some rocker but not a great deal. It flares upward sharply at the ends.

White water outfitters on the Grand Canyon like to put four passengers in the boat (as with boats above) with a support raft coming up behind with tents cots food and drinks. How could you position four pasengers closer to the center of the boat?

One potential solututon would place two rows of two passengers (side-by-side) in front of the rower, with all that shifted back and forth until the bulk of the total paylaod is centered over the middle of the boat. One attrative side effect of that design would be its easy conversion to DIY river running mode, with includes cooler food and camping gear but only two passengers in the boat.

To make that conversion the centermost row of seating could be converted to hold a large cooler and up to four five gallon water cans, with the only two passengers seated up front.

Another as yet unsolved problem will be how to make all seats adjustable fore and aft--over a deck--so the payload could bbe optimized for different passenger sets and different amounts of camping gear. Adjustable positioning is always better than fixed. I'm starting to think I might make all seats as parts of two separate frames, much like a rowing frame on top of a raft.

The rowing frame would have fixed in place oarlock towers. The rower's seat would slide fore and aft on inline skate wheels and the foot rests would adjust with respect to the oarlock towers so the same boat could be rowed by Chris Bosche or Muggsy Bogues. The two rows of passenger seats might have a fixed distance apart but the overall passenger frame itself could be adjusted forward or back. Somehow someway in order to optimise varying loads. Designing the seating details of any dory the hardest part. And the most fun.

Designing on the fly, with full size mockups, is a lot more satisfying then playwing with 3D design software. For me anyway. This boat is about 4" inches shorter than a Briggs. And 18" inches wider.

MRB Whale Rider

18' foot 9" inch side panels. 66" inches wide on bottom. 8' foot beam. Lots of side flare without too much rocker. Fiberglass bottom wooden top. All wooden pieces bolt or screw on over marine silicone caulk so anything and everything can be replaced--with a screw gun rather than a sawsall. Even the 7 layers of ash gluelam gunwales can be removed in a matter of a few minutes.
/fragments/Whale-Rider/twotwo2
two rows of two

Footnotes:

1 Why does spreading the weight out to the ends of a highly-rockered white water dory make it more side-to-side tippy? The radical bottom rocker profile of a white water dory means passengers seated out at the ends of the boat are also placed almost a foot higher than they would be closer to the center. Once a boat starts to list at all that higher weight at the ends becomes a lever that instantly accelerates the tipping. Dories are far better off with their payload centered over the boat's center of gravity, where it is also lower down.

2 If I have this right Martin Litton first asked Keith Steele to make a four passener boat. Keith essentially chopped his famous 15x48 in half and added an addional 3' feet to middle without making it any wider. That boat is (I think) refered to as the "Susie Too."

But Keith Steele had a booming business with his wildly popular 15x48 and he didn't want to make any more long skinny white water dories. So Martin Litton sought out Jerry Briggs to do much the same thing. The Briggs has been the standard Grand Canyon dory ever since.

Briggs boats are long and narrow. If you characterize the hull of any given dory by its ratio of bottom width to overall length, the Briggs is way out at the tail end of that distribution. The Briggs is the longest skiniest boat in the history of river dories. That may or may not be a good thing, depending on how you look at it. But the Briggs is a long skinny boat.

Any discussion of wider vs skinnier is highly subjective. Some, like me, like wider boats. Many others love their Briggs. Wider vs skinnier will be a topic for another discussion at a later date (June 19, 2021 at this writing). Time will tell. Eventually. We'll see.