Hi everyone,

   Hopefully this topic hasn't been beaten to death previously but I'm thinking of building a scaled down version of Jerry Briggs Colorado River dory.  I have a copy of Roger Fletcher's book from which I pulled the dimensions for the 17' version.  My question to those who have built and rowed this boat is this:  The greatest distance between the chines of the 17' version is listed as 46".  If I wanted to build a scaled down 16' version the distance between chines would be around 42 3/4".  Seems narrow...but would it be sufficiently stable (since it was proportionally scaled down) or would the floor need to remain near the 46" mark despite the shortened length. 

   I was also thinking of using 3/8" side panels as opposed to 1/4".  Thoughts if needed or overkill?

   Can anyone explain to me why a transom or double ender may be the better choice of the two?

   One note:  this boat is being built for western Montana and Idaho rivers, not the Grand Canyon.  My wife and I enjoy whitewater and multiday trips and this is how the boat would be used. 

   Thanks for any information that you may deem necessary for this build.

   Craig

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Hey Craig,

My first thought is 42 3/4" is way too narrow. 48" on the 17' is actually on the narrow side. It seems to work in the canyon because running the canyon is more point and shoot than actual maneuvering (never have been there just what I understand).

I doubt you will be able to bend 3/8" ply enough for the Briggs. It has a ton of flair, a ton of bend and a ton of rocker (artificially reduced with the chine dishing).

I would just remove about 2" between each frame to get the 16' length.

Mike

Morning Mike,

   Thanks for the response!  Good to know about the 3/8" ply panels.  I'm planning to build this boat as a stitch and glue and it won't have ribs.  So do you think my best choice would simply be to reduce the length and leave all other dimensions as found in the 17' plans?  If this was your build what would your max. floor width be?  Thanks again!

  Craig

Craig, there has been a lot of discussion on Sandy Pittenridgh's site Montana-riverboats.com on width of boats and how it affects handling. It has been going on for a couple of years. Perhaps no consensus of opinions yet other than the wider the boat the greater the floatation and the less water the boat will draft.

Mike, very often I was able to line up at the rapid, push down on the oars and let the raft do it's thing. However there were also times it would have been nice to be able to maneuver such as in Bedrock when I needed to go right not to the left.

In my experience in the Salmon River drainage of Idaho you run into three different types of conditions. The Middle Fork requires a great deal of maneuvering especially if you are heavily loaded and you think that the rapids will be like those of the Lower Main. The Main Salmon requires less maneuvering and the Lower Main the least, it's more of the point and shoot of the Grand Canyon.

I haven't run many rivers in Montana other the Clark Fork which is either very little maneuvering required unless you are in the Alberton Gorge, which requires a moderate amount. On my first trip down the gorge we ran a 20'+ long J-ring at 800 CFS. It uses long sweeps and you must coordinate movements between the two sweepmen.

Anyway my point here is a high degree of maneuvering may be needed dependent upon which river you are on. I would not want to be limited and I think that if I ever build a boat for big water it would be 50+ inches wide, maybe more.

Rick N

Hey, if your heart is set on Grand style dory contact Andy at High Desert Dories. He has a lot of experience and some great plans to help you find the boat you desire. I row a decked 15' 8" Tatman, essentially a Mckenzie hull with Briggs style decking. It is a quicker boat but will slide off waves if you don't stay on it. I prefer the quicker pivot point and consistently run Cat, WW, & Deso at a wide range of levels. The tombstone transom is a nice luxury to motor big flats at low water. I recently built a Nevill's replica with 3/8" sides, it would be quite a challenge to use 3/8" on Grand style dory.

I also row a decked Mckenzie type hull.  One of my friends has a decked Tatman which has thousands and thousands of river miles on.

The Briggs is fine on the Grand but I find it too slow a boat also.  I have taken my 16 foot McKenzie down Deso back in 2012 when the flow was 900 and when it was 45000, in 2011.   I have rowed it down the Grand also and rowed a 14 foot McKenzie down the Grand in 2010.  I would comment that for me a lows side 14 foot McKenzie is too small for the Grand.  I don't think I would want to run a Briggs boat in low water.  I can't imagine trying to get a Briggs boat down day on of the Middle Fork in low water.  I'm sure many can do it but if I tried I would smash every rock in the river.

Another friend build a Briggs style from plans he got form Andy.  He got plans for a standard and a wider bottom.  He went with the 48 inch plans.  I would have gone wider.  That boat is not up in Jackson and has made a few trips down the grand as well.

Like Marc said, if you take on big waves with a McKenzie hull which has more rocker it can spin on you if you aren't ready.  Got to brace into those laterals.

If you decide to build a smaller Briggs, I like Mikes comment about removing some pace in the center section between the frame segments.  If it's SNG they just estimate a bit.

I did the opposite to build my 16 foot Mckenzie.  I just stretched  a 14 foot design.

   Thanks for the response  You wouldn't happen to have any pics of your 16 foot boat available would you?  On your decked boats, what are you using to waterproof your hatches?  Pics of that too? 

   We did Desolation Canyon last year in August. Man I love the SW!

You can see the build at

mountaindogs.net/plascorehull

It's a composite boat but it would be the same thing in wood.

My hatches need work. I had a lot of water get under the lids in the real big waves. It will be easy to fix, just need to put compression seals in place.

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