frame width

There is lots of discussion on this, including a similar thread in the last few weeks... maybe exactly the same... to be brief usually folks go wider than center to center how much is personal preference (search old threads).

66" would be what I'd put on there with those two choices...

Yes you will have more weight bearing on the cross bars than the side rails, but it will redistribute out quite a bit when you load the boat (depress the tubes and spread weight to the frame rails). It will not stress the frame to do this, the most commonly discussed drawback is wear from the frame on the boat but in my experience the opposite will happen. The frame rails will wear, leaving black marks in the form of oxidized aluminum powder. Soap, water and a Mr. Clean Magic Eraser and the rubber it will look new, while the ends of the cross bars and the low pro's will show obvious wear (loss of annodization at first, then the AL itself).

Melrose: again, just based on my own limited experience, I've been using a 48" wide frame (left over from a smaller raft) on a 51" c to c raft. I strap it to 6 D-rings -- have had no problems but have not had it on especially big water, so I can't speak to how it would behave getting bounced around!
Also, I knew the 51 c to c raft was probably transitional, so didn't want to invest in another frame. Sure enough, just ordered a 60" c to c. It is tempting to go 60" wide NRS because that's what I have on a small cat (blasphemy) and could have interchangeable parts; but the advice here is go 66" over the 60" -- I expect I'll go with what works best (vs. the interchangeability). And it seems easier to go with the standard NRS widths for ease of ordering extra pieces in a hurry. Still thinking...
Thanks all for the advice!

Oh, just FYI, I asked the question to NRS in the context of one of one of their pre-configured frames; here is the response:
.. .there's no "right" answer to this. Of course, you want the frame side rails to come out at least to the center-to-center of the side tubes, but going out beyond that is not a problem. Having the weight rest only on cross members is not an issue. What the choice of width does affect is the areas of the frame resting on the tube that can wear on them. However, if you have wear patch material on top of the tubes any wear is manageable. If you have more questions, just give us a call...

johnovice said:

86-(11+11)=64" c to c, so a 68 wide frame results in 2" wide of center on each side; seems fine. My possible 66 frame on a 60 c to c results in 3" beyond center on each side. I know c to c is considered the minimum; I was wondering how far beyond c to c is still good.
Sounds from the responses here that 3" per side is still reasonable.

Click to expand...

You could go wider if you wanted... but 66" is certainly reasonable, but you could go wider if you wanted. With 22" tubes you could go as much as 6 inches wider the C-C on either side it side decks and such were important to you.

FWIW, I did pretty much what pinemnky did, I drew my boat and frame to scale in ACAD and figured out a bunch of things in the process. It's a good idea if you're trying to maximize space, get things exactly so or what not but its not necessary. You can certainly have plenty of success simply getting a few inches wider than C-C.

My personal preference is for a wide frame and on my new boat I wanted side decks over a double rail frame. The boat is 65" C-C and the frame is 77" wide. It's a wide boat 88" overall with 23" tubes and both sets of rails lie on the tubes. That's how I built it in the end, put the double rails together, set them on the tubes were they wanted to be and measured the spacing. - came out within an inch of my drawing. In the end I adore the width. I have 11" decks on both sides, my kids and dogs walk back and forth all day and in 30 days on the water this year not one of them fell in (pretty remarkable for my family). Now with all that said, my frame, with anchor system, seats, decks and floors weighs about 160 lbs. If I wanted to go light I could get it down to between 70 and 90. The frame Nazi's will explode with laughter at that weight but the result is perfect for my use... So I could give a shit what they say. This is why I originally said it's really personal preference...

Moral of the story is, think about your use and decide if you want; a simple, light factory sizing or if you want something else. The beauty of modular frames is you can make them any size you want, aluminum is easy to cut and easy to drill. If you want a 68" NRS frame buy 72" and cut 4 inches off one end, redrill a half dozen holes and you're good to go. It's not rocket science. 66" will work fine for your boat, but you could go wider if it suited your needs...

I'm of the opinion that either frame will work but not optimally. It's not the biggest deal but the 60 could be squirrelly as mentioned before and the 66 would rest most of the frame weight on the crossbars as the side rails would likely miss the tubes (less stable, potential for increased wear)

Since you are asking 60 vs 66 I assume you are going with a pre-made frame. If it is an NRS I'd just have them make the size you need. I have a 12' Hyside on order that seems about halfway between a 54 and a 60. When it arrives, I will measure the width of the rafts chafer (probably 57-58") and have NRS make a frame that sits just inside the outside edge of the chafer. They don't charge for custom sizes so you might as well take advantage of it.

Then measure where your oar locks end up and do the 1/3 2/3 math for oar length. (+\- for preference).

I was taught early on to fit the frame to the raft then the oars to the frame. To me, doing it any other way is just an series of educated guesses which usually end up at a chopsaw anyway.