Welcome Log In Create A New Profile


damage control/prevention?

Posted by lhedrick 
damage control/prevention?
November 20, 2014 05:04PM
Can we prevent this?

This image is of a boat filled to the top going into the wall at Crystal in the Grand Canyon. Flow about 13000 CFS.

The image shows the gunwale being crushed just behind the oar lock. A few inches forward and the right oar would have been out of commission.

I would like to have a discussion about ways to prevent this kind of damage,,,,, if possible. I have no interest in discussions about the rower, this could happen to any of us, especially me. I got taken into the wall up river at Granite on my last trip and had to deal with a dead boat full of water. You could say I got lucky as the boat went straight down river after coming off the wall. In this case let’s assume a ravin stole the carabineer from the bow line and the boat got away. Yes, they could actually do that and probably with a locking one too.

Sandy, you mentioned running the deck to the top of the side panel, no doubt that could be built up to be very strong and some crushable material added. But, that will require some design/fabrication to build a rowers area which slopes down or we would not be able to lift the blades out of the water.

Let’s also assume that we can’t really make the top side any wider. It’s got to work with 10 foot oars.

The 2 big fears I alway have are:

1) going down into a monster hole which has a rock at the bottom which then comes through the bottom of the boat. ( been there done that at Upset and Hance, lucky there was no rock in the hole)

2) Losing an oar with a boat full of water and get taken into a rock board side with the full force of the current push the gunwale into the obstacle. This one can destroy absolute anything in a narrow rapid where we can easily be going 15 MPH.

If we have a design where the deck meets the side wall like your 1 man boat, Then we could add a 4 foot long, inch thick piece of some crushable material. Like aluminum honeycomb/stainless honeycomb, dense crushable foam etc. Then cover it with a strip of thin 1i nch wide aluminum bar stock. It could be bolted on making it replaceable.

We shouldn’t really need it anywhere but the center of the boat. If we smash something up front, the boat should pivot around it. Damage for sure but much less then right at the center.

I know what’s coming “just learn to row better” thanks for nothing on that one. Some of us might only get a few chances at a big runs over 5 years. Not like we can go practice 10 times before we go so lets leave that issue out of the discussion. You can’t become an expert without taking on some big rapids before you are really ready.

Re: damage control/prevention?
November 20, 2014 07:08PM
Looking at those photos, I wonder if one of Sandy's outrigger oarlocks (in a previous thread) would have made the situation better or worse structurally at impact. They would make the boat a few inches wider.

One could imagine packing a spare outrigger in the boat in case of catastrophe. Rob Anderson
Re: damage control/prevention?
November 20, 2014 08:30PM
Anything sticking past the gunwale isn't going to be there for long and it will be a lever arm to break even more stuff. If you have a spare there might not be a side wall left to attache it. It has a place but not here.

Sandy's idea of getting rid of the gunwale and placing the deck up at the top of the side panel and glassing the crap out of it has merit but adds some new problems. If the deck goes up then where do we lash spare oars (which are not optional). If we lash them to the deck and the deck goes up they will prevent us from pushing down the oars to lift the blades out of the water. I already have trouble with this issue.

Not as simple a problems as it might seem. With the side panel 3 inches above the deck, a hit can break it off down below the gunwale.

We could use angle brackets to brace the side agains the deck. The big problem is that any material which can't flex must have enough strength to survive the hit or it will break. So ether we add more material to send the load away from the point of impact or we add something which can take away the energy by crushing.

Lets say, we get to Horn Creek, we scout, it’s your first shot in 5 years and the critical section of the run lasts about 1 second. Your first big pull is make or break as to whether you can cross below the right horn to the safe left line. I am 6 foot 3 230 pounds and lift 5 days a week. I have a strong pull and can make that run even if I am a bit late. A 150 pound rower has a tougher time. If you don't make it you are going down the right side and it's huge. Last time there we watched a guy rowing a cat, he didn't make the move and got pushed broad side into the big flipper rock bottom right. If he had a dory, he would have had some major damage. It is correct to point out that if you get pushed off line and can stay cool and take what you have left you can maximize your changes. But,,,,,,,,, if you are great oarsman and get washed off the boat, which I have seen happen, a passenger with lesser skill may need to take the oars and hang on. The stronger the boat, the better. I am ready to trade off light weight for more strength.

As for rocks in the bottom of the holes, yes the rock is usually what makes the pour over and they are not usually at the bottom of the hole. For those who have been down the Colorado, remember Sockdolager and the big wave just after entry? One time I took on the wave straight up, I was right on line. I dropped the oars into the water to push up the wave and placed my right oar on top of a rock just a few feet to my right. It was likely only 1 foot below the surface. Never saw it and by not it might have been flushed down river. There might have been enough water to float over it but to sure with a heave boat. That rapid requires some forward speed to get over that wave. We start pushing early to build speed. If we hit that rock with the fast current not sure what it might do the bottom.

The damage to the bottom of Kelly's boat was substantial. At least all that need be done was to dry it out epoxy the plys and bond them back to gather. I don't think that damage would have been near as bad with 1 inch plascore. It might have only been a dent on the out side .

Re: damage control/prevention?
November 20, 2014 09:46PM
If you attach a deck right to the top of the side panels the boat might not have to be so high overall. Let the water wash over as much as it wants. Just a thought.

RE> "rower too high"
The rower does not have to sit any higher. You just have to make the rowing area recessed down a few inches, with all of the recessed area sloping down to the bottom of the foot well...........which has a 4" inch PVC drain pipe going straight down so it drains almost instantly. If the boat draws 4" inches of water there will be 4" inches of water in the bottom of the vertical drain to the foot well area. So what. Your feet (and the bottom of the foot well area) are still 8" to 10" inches above that.

RE> "were to put the oars" ........... there's always a way. Gunwales on a decked boat are tits on a bull. Heavy and a lot of useless work too. I think. I have to finish my next boat project and then row it some before I can really claim that. However. As you mentioned--it seems to work just fine on my one man. I'm finishing up flush latches and hinges on the lids today and tomorrow. Then I'll put the little one man boat outside the shop and start on a bigger one. I do have all the materials now. On hand and ready to go.

RE> "outrigger oarlocks" On many boats I've seen, including Dave Inskeep's and at least one of Jeremy's, the oarlocks were welded aluminum towers that slant up and out from just inside the gunwale. No? Don't I remember that right? My outrigger oarlocks (that protrude 4" inches past the top outside edge of the boat) are no more vulnerable than those aluminum towers. Perhaps a guy has to put a spare oarlock mechanism in the bottom of the boat, along with a few misc bolts. Along with the expected resin and glass. Just in case.

If you don't buy the above outrigger argument the oarlock holes just have to be bored right down through the deck, maybe 2" in from the outside edge. Line the bored hole with a brass or PVC sleeve and reinforce the shit out of it below the deck. You'd have to put those oarlock holes in a place where you could reach the bottom of the oarlock pins, so you could put a retainer ring on the bottom of the pin..........albeit below decks. Just have to keep it within 12" inches of a hatch opening.

A curved deck that goes all the way across from top-outisde edge to top-outside edge is the strongest way to go. That's self evident. The rest--the details after that--amount to problem solving and creative engineering.

Re: damage control/prevention?
November 20, 2014 10:11PM
Dave and Jeremy use the pin and clip setup. I really hate those things. The plates mount inboard of the gunwale, not sure if the top of the pin actually angles out past the gunwale but it's close. One thing I know for certain If that setup flips and a boat floats in a big rapid upside down and a pin which sticks up 10 inches above the deck comes in contact with rock it's going to be a problem. In their cases, with their skill and the way they look for the safe line I think the changes of their boats going over are low.

I don't know when I will build the next boat so you will be ahead of me on finding some of the needed solutions. Good timing on my part since it will give me time to deploy your solutions.

As for the spare oars. Last time we rowed Hance, Pearl entered before I did. He was a bit late and bit right. I watched the current grab him and start to take him down the right side. He was pulling like crazy and not moving left. Shortly after that he pulled so hard he snapped one oar off just below the lock. I then knew to go earlier and start a bit more left at the entry so his misfortune became my easy move left. He was able to get one of his spare oars free and into place. So my idea of stowing a removable blade under the deck is not a good idea.

I have been wondering for some time how to mount the spares for fast access. I though about making a pocket on the deck for the blade to recess into. Then there is the issue of the spare oars often wind up on top of side hatch lids cutting off access. Just not enough real estate to easily get it all figured out.
Re: damage control/prevention?
November 20, 2014 10:45PM
One more thought, about the top edge to top edge deck idea.

Your boat and all other decked boats I've ever seen have a flat deck, more or less parallel to sea level, positioned 3" inches to 4" below the gunwale at the oarlock position. Usually lower down from the gunwale yet out near the ends of the boat. So. You have a flat deck with the sides of the boat extending upward past the deck. What good does that do? When big water washes over the sides of the boat it gets trapped inside that big bathtub like deck. And stays there until drains that are invariably too small do their job.

If the deck stayed exactly at that same height, above the water line, but did not have sides extending up another 6" inches or so above that, the deck would drain instantly. There would be no bathtub effect. Foot wells for rower and passenger areas will of course fill.....in both arrangements. With or without a gunwale. But the bottom of all such recessed areas should be kept (it seems to me) as high as is comfortably possible, so the bottom of each recessed foot well was well above the water line. You still want to keep the payload low so all that means is the legs have to stretch out forward a bit more, and less straight down. And then, in the bottom of each such foot well area, drain it with a 4" vertical pipe. If you're worried about odds and ends falling down the 4" inch drain pipe put some 1/4" plastic mesh over the top. Most foot wells I've seen were not adequately drained.

The top of the boat shouldn't be a giant dishpan. It should be the top of the boat. So water washes right over, without getting trapped.
Re: damage control/prevention?
November 21, 2014 02:56AM
The flat deck was for one purpose, to make it easy to sleep on the deck where it's cool at night. There is enough room on the deck of my boat to put my small tent on top. But,,,,,,,,,,,,, since the Grand is so damn hot in summer. I have a filler cover for the foot well but, I will never go back in summer so for me that's not an issue. Two summer trips and never again.

That vertical foot well drain makes sense. I didn't do it just because I couldn't seem to deal with the idea of a hole in the bottom of the boat to snag rocks. Probably not and issue. And your right about the foot well high, it needs to be as high as possible.
Re: damage control/prevention?
November 21, 2014 02:37PM
RE> "center of gravity and low down passenger weight"

Absolutely. The higher the payload the more unstable the boat. I'm don't plan to put the rower or the passengers any higher. I'm thinking car seat instead of rocking chair. In a car your legs extend forward so the distance between your bung hole and the floor of the car is less than a dining room chair. That's one way to keep the passenger at the same height and STILL raise the floor of the foot well a good 3" inches or so. And then drain it well. I've been in too many boats (one anyway) where my feet were in a pool of water half the time. The photo above, at the start of this thread, must be a frame capture from a GoPro vid. One of those frames shows a large amount of water trapped on top of the deck, sloshing around between the gunwales.

If there was no gunwale--if the boat was more Grand Canyon old school as you mentioned--with the deck being the top of the boat, that water wouldn't be there I don't think. I guess my point about sides and guwale extending above the deck is twofold: A) it traps water, temporarily anyway and B) what does it accomplish? Why do anything that adds both work and weight..............if it accomplishes nothing?

You need a guwale on an open boat. That's where the stiffness comes from. But on a decked boat it doesn't compute for me.

Re: damage control/prevention?
November 21, 2014 07:37PM
Hey I don't want this to be an argument. But I don't agree. If the passengers sit with butt not moved and all you do is move the feet up a few inches you haven't changed the center of gravity. Not in any significant way. But you have reduced the number of gallons of water the sitting well can hold. Those passenger sitting wells do not have to extend all the way from side to side either. A 17' foot boat is wider than the space needed to sit two passengers side by side. Making any sitting positions wider and deeper than they need to be just increases the amount of water they'll fill up with. Which makes the boat that much more unmanageable for a few (sometimes critical) seconds, every time the front of the boat plunges down and then back up again.

You might have a point about making it harder to high side from that position. I'll think about it. A more car seat like position could and would still include a flat spot, so those passengers could stand up and stretch at any flat water time they want. I looked at Jeremy's very well built Briggs two years ago. The passengers were seated down low. Which is good. But still. Those areas clearly got swamped with a lot more water than they had to.

I still take my waves and wet chances with a no-gunwale boat. When it's big water you are going to get wet no matter what. I have rowed the Briggs. It is slow to turn. Very slow. Makes you feel like you need to do more weight lifting just to get it from here to there. And it is surprisingly side-to-side tippy for such a big boat. I think I can make a better boat. One that's more nimble on the oars and not so side-to-side tippy. Time will tell. :=))

Jeremy and Larry both took 15' foot decked Honky Dories down the Grand. And lived. They both said it was NOT well suited to the job. But good enuf. It was too small and too easy to spin. So they spent too much time constantly adjusting boat position in swirling currents. Easy to spin is good on rock garden day trips. I can see how it might be a bit too much on a three week Grand Canyon trip. There has to be a happy medium between spins-on-a-dime like the HD, and frozen molasses slow like the Briggs.

I rowed the Susie Two too. Is that any different than a Briggs? I rowed them so many years apart I can't remember. I rowed the Susie Two replica when it (what was the builder's name? Somebody Frye?) was brand new. Just around a bit of flat water I admit. But a sports car it was not. Even in flat water I had to pull on the oars like I was pulling a tooth out of a woolly mammoth. I remember rowing it I had to bite my tongue, because I didn't want to insult somebody's brand new boat.

PUNCHLINE: I think the Briggs is as slow to turn and maneuver as it is because A) it is narrow for its length so it sinks down further into the water. Wider would bring it up closer to the surface and B) the flat spot in the middle means there is no clearly defined turning axis, and it also means you have to push more water with the chine as it turns and C) when fully loaded it puts the payload too far from the center of the boat

Re: damage control/prevention?
November 21, 2014 08:50PM
This is a fun discussion for me because I'm close to getting started on a decked 17' foot project. All this back and forth helps me a lot. Jeremy Christensen's Briggs was an impressive boat. Jeremy really did good work. I noticed and liked and respected the way the passenger seats were placed low down in the boat. Yes. That makes the most stable boat.

However I was skeptical about where those passenger seats were placed. In addition to the rower's seat there were two passenger sitting wells fore and aft so a maximum payload would be two up front and two sitting behind the rower. Five humans total, for a maximum load.......I take most of those boats go down the river with minimal gear, which is usually freighted downriver in support raft. The passengers are the only payload. I suppose it is a bit different for outfitter-yourself trips where you can move cases of beer around to custom trim the load.

Anyway. A.J. DeRosa has a six man passenger bus designed and built by Cyrus Happy. Ray Heater's partner. I rowed that boat. I rowed it alone, without passengers. But I did row it and I was amazed at how nimble it was and how easy it was to slow down. AJ says it doesn't row that much differently loaded. I think that boat is 18' feet long overall. Must be made with 20' foot side panels. I really don't know how wide it was but it is wide. Eye bulging wide. It really catches your attention when you first see it. The rower sits surprisingly far back--behind two rows of three seats. That way the payload (which is potentially 50% bigger than the Briggs) is all concentrated as close to the center of the boat as you can squeeze it. Squeezing the payload over the center of the boat combined with extra extra width and a well designed rocker profile made it a remarkably successful boat. Hats off to Cyrus Happy. He designed a one-of-kind, never-built-before boat that is a real performer.

Conversely the further out toward the ends of ANY boat you put the payload the harder it is to turn and the more side to side tippy it is. I think any new start from scratch white water dory design project has to envision its role (and roll). What will be the maximum payload? What will be the average payload? What ever the answer I'm confident the best boat puts that payload as close to the center of the boat as is comfortably possible. The further out toward the ends of the boat you put that payload, the more worser it gets.

Re: damage control/prevention?
November 22, 2014 09:36PM
Well, Jremey built a conventional Briggs. The guides often have 4 passengers. They don't row private trips with a loaded boat and only 1 person up front.

So your comment about the front passengers area being bigger then needed is right on the money. I built lash points for 2 5 gallon water containers in that area. Big mistake, another 80 pounds up there is no good when I have too much rocker in the hull. The simple answer to that is to move the water containers under the center and lash light dry bags up there which will also displace water when it takes a wave.

It's clear the Briggs rows as it was intended, straight down the flow. With all but just a few rapids on the Grand they are pool and drop. Down the tongue and keep running the line. It's perfect for those conditions. Not worth shit on day 1 of the Middle Fork at low what when you are moving around rocks all day.

There is also lots of talk of the merits of the 48 inch bottom. That was not a design consideration. It's only that way because of the plywood size and a 48 inch bottom is going to make it sink lower into the water. Make it longer to float it back up and it will turn even slower. 56 inch wide makes everything better.
Sorry, only registered users may post in this forum.

Click here to login