kwaggs
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Post by kwaggs on Mar 26, 2014 9:19:29 GMT -8
Has anyone thought of or actually put a canoe rack with a canoe on top of a Shasta camper before? Just trying to think if the framing was supported enough before the skin was put on it, what would be the dangers of putting a canoe on top, besides height?
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SusieQ
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Post by SusieQ on Mar 26, 2014 11:03:28 GMT -8
I'm sure it could be done. But I wouldn't. Yakima makes racks for teardrops that work quite well. They attach to to the side of the roof framing.
I wouldn't on the Shastas for a couple of reasons, one being if it is stick framing like the Compacts, I wouldn't trust the added weight. Two, it would not be very aerodynamic. Compacts aren't aerodynamic to start with and the front is actually taller. True canned ham's are much better in that aspect. I do not think it would pull well with the added resistance.
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Post by bigbill on Mar 26, 2014 12:47:59 GMT -8
Back in the day a lot of people hauled canoes and small alum boats on top of Shastas. A guy that used to come to the lake where we went had a mount that fastened to the trailers rear bumper then the boats transom clamped to it like a motor mount. Next he lifted the front of the boat up and swiveled it around so the front set on a cross rack that was bolted to the trailer. Had brackets on boat that bolted to the trailer rack. He could load or unload it in just a few minutes by himself. He claimed it made the trailer tow better, don't know but I guess anything is possible.
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SusieQ
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Post by SusieQ on Mar 26, 2014 13:38:21 GMT -8
Here's a rack on a teardr op:
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pathfinder3081
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Post by pathfinder3081 on Mar 26, 2014 16:00:15 GMT -8
I know that it can be done.. I would not. There was the time when I would not buy a vehicle unless it had rain gutters on it.. (for roof racks) One slip loading or unloading with a white water boat and BAM! You got a huge dent in your camper. If you pull with a truck, rig you out a rack for the stanchion holes. 2x4's simple and you can move you boat forward a long ways. Ratchet her down and you are good to go. Same placement with a car top rig but you might have to drop a few bucks for a good Yakima rig or one like SzQ pic'ed. (look like Yakima) Good luck and see you on the river..
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kwaggs
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Post by kwaggs on Mar 26, 2014 17:29:23 GMT -8
I have re cornered my campers framing with 1x10's and added extra vertical support framing throughout the camper and I have used 1x4 red oak across the top from wall to wall so I was thinking that the extra framing strength could hold a canoe if I built a rack for one. Just thought I would ask if anyone has tried this before. I have a Jeep cherokee and if I put a canoe on top of it I dont think I would be able to turn a corner with the camper without pushing the canoe into the front glass of the camper. I have an Airflyte, I dont know if that matters at all but I appreciate the response to the question.
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mobiltec
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Post by mobiltec on Mar 27, 2014 19:14:37 GMT -8
The only thing I would be worried about is leaks because of the vibration caused when you are driving down the road... So you will have to think about maintaining the attachment points. Sounds like you beefed it up enough so go ahead and do it and let us know how it works. Remember we want pictures. Watch out for low trees.
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Bow_Tied
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Post by Bow_Tied on Mar 29, 2014 8:44:28 GMT -8
The pic SusieQ posted shows brackets that are good from an engineering perspective. Keeps the weight transferred to the walls and not the roof. Lower the profile the better. I'd make it so that your straps tightened the canoe to the rack itself only and not to anything else. So long as the rack is properly mounted this puts no added stress on the walls of the camper from the straps. JMO
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cowcharge
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Post by cowcharge on Mar 29, 2014 8:56:55 GMT -8
I'd be hesitant because of the aerodynamics.
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Post by bigbill on Mar 29, 2014 20:24:46 GMT -8
I believe that if the canoe was mounted with the front hanging over the front of the trailer just a little and it was tested in a wind tunnel you would discover it improved the aerodynamics of the entire unit. I could be wrong on this but I think I am right. The only way to tell would be to make a scale model and actually put it in a wind tunnel but I don't have access to one anymore. Any engineering students out there that needs a project?
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SusieQ
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Post by SusieQ on Mar 30, 2014 5:14:32 GMT -8
I believe that if the canoe was mounted with the front hanging over the front of the trailer just a little and it was tested in a wind tunnel you would discover it improved the aerodynamics of the entire unit. I could be wrong on this but I think I am right. The only way to tell would be to make a scale model and actually put it in a wind tunnel but I don't have access to one anymore. Any engineering students out there that needs a project? Takes an engineer to think like an engineer. You have a point there. I was thinking about it being mounted parallel with the roof line. But, if it were parallel with the street, it might be OK or better.
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Post by bigbill on Mar 30, 2014 5:56:28 GMT -8
what I was thinking was the tow vehicle would already be splitting the airflow then as it would start to close in on the front of the trailer the bow of the canoe might act as a wedge continuing the split in the flow making less drag on the trailer. Not certain just thinking which usually gets me in trouble.
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Bow_Tied
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Post by Bow_Tied on Mar 30, 2014 7:32:50 GMT -8
I would be surprised if it helped. The canoe could be considered a slippery shape and maybe it would lend to air flow well off of the tow vehicle depending what kind it was. However, since drag is also a function of frontal area you can't get by that there is a new square footage being added to the air flow. However the net difference in consideration of the brick being towed would likely not be significant. If it was noticeable, one could simply slow down a little bit to negate the difference since drag is relative to the velocity squared - the faster you go the drag gets much worse.
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Post by bigbill on Mar 30, 2014 16:07:40 GMT -8
I don't think it would make a major difference but it could cause the air flow to not make contact with as much of the frontal area of the trailer so by your own formula you might decrease the effective frontal area similar to the point on a super sonic jet. I don't think it would do anymore than offset the extra drag the canoe creates. To know exactly you would need to know the exact shape of the tow vehicle, any mirrors or other things protruding into the air flow, the exact distance from the tow vehicle to the front of trailer, the height and width difference, the exact shape of the canoe, and how high it is mounted over the trailer plus how far it sticks over the front and rear of the trailer. With all of that information and a good computer or a dozen pencils you could make a better guess. The simple way would be a model in a horizontal wind tunnel and run a smoke test. I personally don't care enough to find out as I don't have access to a wind tunnel or a model to outfit with a removable canoe. I just started this with a causal comment. You are exactly right in what you say, with or without the canoe you will do better a a lower speed to a point. All of the above isn't important, if you want to save fuel buy a small car and don't pull anything. but it is fun to ponder the results of random ideas now and then. That is how many great advances in everything from space travel to bicycles has been developed.
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cowcharge
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Post by cowcharge on Apr 4, 2014 7:18:23 GMT -8
Don't forget the added drag and turbulence from the canoe rack.
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