Effect of scratches on canoe efficiency

[BobMills]

I'm sort of like dougd - I just plug along scratches and all. I've never purchased a new canoe so almost all my canoes came pre scratched so I've never reached maximum speed. I have had a couple of deep scratches which I filled with bondo and sanded down until it seemed smooth (I don't know what grit I used). The canoe I'm referring to is an old kevlar souris river prospector - when I bought it it was faded so I painted it. Every couple years after I've worn the paint off the bottom I sand it down and repaint and it looks shiny and sort of new. I have better looking canoes, but I'm attached to this one - I even named it.

 

[Steve in Idaho]

When I'm paddling, the drag that threatens to tire me isn't between my scratched hull and the water. It's what's above the water that causes the problem. No amount of sanding and polishing is going to help that.

Afraid I'm going to have to disagree with JW if he believes scratches make more difference than hull design - above or below the waterline. Poling upstream, where, in ppractice, speed on the water often exceeds theoretical hull speed, a scratched and dented Penobscot moves against the current noticeably easier than a pristine new Prospector. And well below hull speed, glide is still better.

Whether or not scratches noticeably increase drag enough to matter outside of Olympic class racing, I couldn't say. But I'm sure not noticing anything at my speed. My current Malicite has almost no scratches, but the previous one had a pretty scratched up bottom. Nope. Didn't notice a difference. Neither have I noticed any of my boats getting slower.

Maybe it's just 'cause I keep getting better.

 

[gumpus]

I found an old post stating that Eric Nyre was able to measure an effect from scratches on coast down friction in kayaks. My take is that it is hard to measure with confidence so probably a relatively small effect. I paddle with a 60 pound dog that adds noticeably to the glide of my solo canoes and it's hard for me to believe that scratches could have anywhere near as big an impact, but I could be wrong.

I like the statement in the link from frozentripper saying " if a boat feels right for you it probably is right". JW made a statement that "it's hard to know exactly how a boat will be used" and Dave Curtis recently said that a boat is designed " for most people and most situations". I'm happy with my boats for my use and not too worried about scratches.

Hey frozentripper, my favorite quote from the link you sent is "you will never feel a great paddle"!

 

[yellowcanoe]

JW and David Yost have different approaches to design
DY has a specific paddler or profile in mind. I am fortunate to be able to grab his ear from time to time in person and I'm able to ask "who did you have in mind for that design"
Lately his answer has been for the older rounder less skilled soloist. Not an insult. Just the real canoe customer

 

[frozentripper]

Hey frozentripper, my favorite quote from the link you sent is "you will never feel a great paddle"!

Hm, well, I don't remember that bit, maybe referring to how paddling never feels great when there's always too much power needed to overcome the effect of all that danged scratching slowing things down.

Depends on the context too, like saying that you have scientific proof that the canoe's been safely beached when hull resistance increases dramatically. Much more power needs to be applied to keep the canoe moving forward. Yeah, that's measurable and scientifically defensible evidence of beaching. Something like scratching, I guess.

 

[gumpus]

JW and David Yost have different approaches to design
DY has a specific paddler or profile in mind. I am fortunate to be able to grab his ear from time to time in person and I'm able to ask "who did you have in mind for that design"
Lately his answer has been for the older rounder less skilled soloist. Not an insult. Just the real canoe customer

One of my favorite canoe dealers also told me that some newer solos are designed to be more friendly so they don't scare first time buyers and I also see some set up for sitting instead of kneeling apparently for same reason. I tried but did not like a couple of the new Northstar solos but again that's just my personal preference.

 

[gumpus]

Hm, well, I don't remember that bit, maybe referring to how paddling never feels great when there's always too much power needed to overcome the effect of all that danged scratching slowing things down.

Depends on the context too, like saying that you have scientific proof that the canoe's been safely beached when hull resistance increases dramatically. Much more power needs to be applied to keep the canoe moving forward. Yeah, that's measurable and scientifically defensible evidence of beaching. Something like scratching, I guess.

Sounds like you've been beaching your canoe bow first when theory says you should be beaching stern first to optimize your scratches.