Hi there. I'm having a hard time getting my head around where I want to mount the seats on my canoe. I've looked at the calculations you're supposed to use and I only get more confused. If someone out there is willing to help here are the details...I'm about 250lbs and my primary paddling partner is about 150lbs however the bow paddlers may range up to about 200lbs (let's say split the difference and use 175 as the number here). The canoe will be used for tripping, hunting and fishing so there will be varying degrees of gear in the boat that will affect the bouyancy/stability. I plan on using 6" carriage bolts to mount the seats to the gunnels. Ok, given that information can one of you math wizzes give me an assist? Thanks
ruso
Seat placement on my Freedom 17'9"
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Patricks Dad
- Posts: 1476
- Joined: Wed Oct 13, 2004 1:11 pm
- Location: Warrenville, Illinois
Re: Seat placement on my Freedom 17'9"
Here's how I would approach this....
1st, ignore the gear you will carry (especially if you ever intend to paddle with little or no gear).
Look at the placement proposed in the plans provided by Bear Mountain Boats, I'll bet they have been well thought out and generally a good starting point.
Find a comfortable placement for the bow seat which leaves sufficient leg room for your tallest bow paddler. Mark this spot (don't cut or drill anything yet).
Next measure from the front of the bow seat to the center of bouyancy of the canoe (you could also use about 2" behind the front of the bow seat - but be consistent with the stern seat if you do - you're just looking to measure the distance between the center of bouyancy and the center of gravity of the bow paddler which is usually near the front of the seat).
This distance times the weight of your bow paddler (175 pounds) is a key number. write it down.
Next divide the number calculated above by your own weight (the stern paddler = 250 pounds). This will give you the distance from the center of bouyancy back to the front edge of the stern seat.
This method will ensure that your bow paddler has enough leg room and that the torque around the center of bouyancy exerted by both you and the bow paddler are equal and opposite (Bow paddler weight X bow seat distance to center = Stern padler weigth X stern seat distance to center).
This will result in a balanced craft in the water with no other gear added. It should float with those 2 paddlers at those positions with the same "attitude" (albeit a bit lower in the water).
Now, step back and take a look at what this does for you. The stern seat will be closer to the center than the bow seat (your larger weight will need to be closer to balance the lighter bow paddler). If you think the placement of the stern seat is too far forward (i.e., if there's lots of room behind you), move it back a bit (if you need to move fore or aft to juggle with scuppers, go ahead).
As you move the stern seat backward (should you feel the need), you will have to think about adding weight in front of the center of bouyancy to keep things balanced (such as gear). If you plan to paddle without any gear at times, then this moving of the stern seat backward would need to be compensated by moving the bow seat forward some (1 inch back on the stern seat would require 250/175=1.4" of movement forward of the bow seat).
Once you are happy with the tradeoffs you may need to make, think about how much your gear will weigh and how it will be packaged. For example, if you put it all in say 2 packs and each weighs about the same, can they be placed in the canoe such that they are symmetric about the center of bouyancy? If so, you're still good. If they are different weights, can they be placed in the canoe such that the torque around the center of bouyancy is maintained? if so, you're still good again. (same math as with the paddler's weights and their distance from the center of bouyancy).
If you always plan to paddle with gear, you can bring that fact into the placement of the stern seat earlier in the process.... (i.e., you can move the stern seat back if you add weight in the form of gear in front of the center of bouyancy - same math applies).
The sum of all torque's about the center of bouyancy should be roughly zero (250Xdistance to stern seat -175Xdistance to bow seat + gear weight aft of centerX distance - gear weight fore of center X distance)
If you have lots of small packages in your gear, you can use it freely to compensate for different paddler's weights (or changes in your own weight). by how you place them in the canoe.
Once you've done all this science, put the canoe in the water with the seats clamped to the top of your gunwales and try it out (note that you will have a much higher center of gravity with the seats mounted that high so be careful). see how she sits in the water empty, with you and a partner and with gear distributed until you are happy.
Note also, that depending on wind and other conditions, you may want to load the canoe differently to take advantage of imblanced circumstances to help you better control the craft.
I hope this helps (but upon reading it myself, I worry that it's a bit confusing.. sorry if it's not helpful).
best of luck.
Where in SW Wisconsin do you live?
1st, ignore the gear you will carry (especially if you ever intend to paddle with little or no gear).
Look at the placement proposed in the plans provided by Bear Mountain Boats, I'll bet they have been well thought out and generally a good starting point.
Find a comfortable placement for the bow seat which leaves sufficient leg room for your tallest bow paddler. Mark this spot (don't cut or drill anything yet).
Next measure from the front of the bow seat to the center of bouyancy of the canoe (you could also use about 2" behind the front of the bow seat - but be consistent with the stern seat if you do - you're just looking to measure the distance between the center of bouyancy and the center of gravity of the bow paddler which is usually near the front of the seat).
This distance times the weight of your bow paddler (175 pounds) is a key number. write it down.
Next divide the number calculated above by your own weight (the stern paddler = 250 pounds). This will give you the distance from the center of bouyancy back to the front edge of the stern seat.
This method will ensure that your bow paddler has enough leg room and that the torque around the center of bouyancy exerted by both you and the bow paddler are equal and opposite (Bow paddler weight X bow seat distance to center = Stern padler weigth X stern seat distance to center).
This will result in a balanced craft in the water with no other gear added. It should float with those 2 paddlers at those positions with the same "attitude" (albeit a bit lower in the water).
Now, step back and take a look at what this does for you. The stern seat will be closer to the center than the bow seat (your larger weight will need to be closer to balance the lighter bow paddler). If you think the placement of the stern seat is too far forward (i.e., if there's lots of room behind you), move it back a bit (if you need to move fore or aft to juggle with scuppers, go ahead).
As you move the stern seat backward (should you feel the need), you will have to think about adding weight in front of the center of bouyancy to keep things balanced (such as gear). If you plan to paddle without any gear at times, then this moving of the stern seat backward would need to be compensated by moving the bow seat forward some (1 inch back on the stern seat would require 250/175=1.4" of movement forward of the bow seat).
Once you are happy with the tradeoffs you may need to make, think about how much your gear will weigh and how it will be packaged. For example, if you put it all in say 2 packs and each weighs about the same, can they be placed in the canoe such that they are symmetric about the center of bouyancy? If so, you're still good. If they are different weights, can they be placed in the canoe such that the torque around the center of bouyancy is maintained? if so, you're still good again. (same math as with the paddler's weights and their distance from the center of bouyancy).
If you always plan to paddle with gear, you can bring that fact into the placement of the stern seat earlier in the process.... (i.e., you can move the stern seat back if you add weight in the form of gear in front of the center of bouyancy - same math applies).
The sum of all torque's about the center of bouyancy should be roughly zero (250Xdistance to stern seat -175Xdistance to bow seat + gear weight aft of centerX distance - gear weight fore of center X distance)
If you have lots of small packages in your gear, you can use it freely to compensate for different paddler's weights (or changes in your own weight). by how you place them in the canoe.
Once you've done all this science, put the canoe in the water with the seats clamped to the top of your gunwales and try it out (note that you will have a much higher center of gravity with the seats mounted that high so be careful). see how she sits in the water empty, with you and a partner and with gear distributed until you are happy.
Note also, that depending on wind and other conditions, you may want to load the canoe differently to take advantage of imblanced circumstances to help you better control the craft.
I hope this helps (but upon reading it myself, I worry that it's a bit confusing.. sorry if it's not helpful).
best of luck.
Where in SW Wisconsin do you live?
Re: Seat placement on my Freedom 17'9"
Randy, thanks for your thoughtful response. I'm just now getting to mounting the seats after doing some other work. If I look at the plans it says mount the stern seat 65" from the center of the canoe to the back of the seat. That just doesn't look right perhaps because I have large decks (~20"). If I look at the bow seat they say a variance of 42-48" is recommended. If I take the calcaulation you provided and take 48" (forward most seat location) x 175 (weight of bow paddler) I get 8400 and if I then divide that by my weight I get about 33 1/2" from the center of the canoe to the front of the stern seat. Does that sound right? That's a far cry from what the plans suggest. BTW Randy, I'm in Arena and about a mile from the river. I hope to clamp the seats in and float it next week sometime once I can decide on a sensible seat location. Thanks again
ruso
ruso
Re: Seat placement on my Freedom 17'9"
Hey all...I was hoping someone could weight in on this as I was hoping to install seats tonight. Thanks in advance.
ruso
ruso
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Patricks Dad
- Posts: 1476
- Joined: Wed Oct 13, 2004 1:11 pm
- Location: Warrenville, Illinois
Re: Seat placement on my Freedom 17'9"
Ruso,
Sorry for not responding earlier (was out for a week of wilderness paddling and just got back yesterday).
I think your math is mostly right. Look at your plans for a center of bouyancy. For a symmetric hull, it would be in the center of the craft. The Freedom is not symmetric so I would guess the "center" will not be exactly in the center of the canoe (I would guess it should be somewhat aft of center).
Measurements I've described above should be taken around the center of bouyancy. But I doubt that this difference will change radically your math (but please check and rework if center of bouyance is different than physical center). The biggest problem you are facing is the significant difference between your weight and your partner's weight. You will likely end up needing to compensate for this difference with more than just seat placement. In otherwords, it will be a combination of seat placement and gear placement in the boat. As I noted in my original post, you could place additional weight in the front to compensate for the heavier stern paddler / ligher bow paddler combination.
Do the same math using the seat placement shown in the plans (using the front edge of the seat in both cases to measure the distances to center of bouyance). Calculate how much additional weight you will need to add to the front to balance things out.
[ (250 * Stern plan dist) - (175 * bow plan dist) ] is the deficit you need to work on. A weight Z placed Y inches from the center of bouyancy should balance things out. Z * Y should equal this deficit. You can experiment with different weigths and distances (lower weigth would require it to be placed farther toward the bow).
This would allow you to put the seats at the plan positions. But it may result in significant weights being required (which may or may not match what you actually want to carry). So, move the stern seat forward somewhat to lessen the amount of forward weight to carry or reduce the distance needed for the weight.
I suggest you take a level with you. Measure the "attitude" of the craft in the water when it's empty and work to match that attitude with you, your partner and any needed extra weight while on the water. For extra weight, consider just bringing a 5 gal water jug along and fill it with water from the river and move it around to see what you come up with. The most important thing is to ensure that when you're done, both paddlers feel like they are in a reasonable paddling position. You set the seats in a "reasonably comfortable positon" before you get near the water. You can also calculate what type of extra weight you will need and where to put it before entering the water. There is really less science involved here than I'm making it out to be.
I have a house on Lake Redstone a bit north of you. I've paddled the Wisconsin River past Arena many times. It's a wonderful resource. We should get together some time.
Sorry for not responding earlier (was out for a week of wilderness paddling and just got back yesterday).
I think your math is mostly right. Look at your plans for a center of bouyancy. For a symmetric hull, it would be in the center of the craft. The Freedom is not symmetric so I would guess the "center" will not be exactly in the center of the canoe (I would guess it should be somewhat aft of center).
Measurements I've described above should be taken around the center of bouyancy. But I doubt that this difference will change radically your math (but please check and rework if center of bouyance is different than physical center). The biggest problem you are facing is the significant difference between your weight and your partner's weight. You will likely end up needing to compensate for this difference with more than just seat placement. In otherwords, it will be a combination of seat placement and gear placement in the boat. As I noted in my original post, you could place additional weight in the front to compensate for the heavier stern paddler / ligher bow paddler combination.
Do the same math using the seat placement shown in the plans (using the front edge of the seat in both cases to measure the distances to center of bouyance). Calculate how much additional weight you will need to add to the front to balance things out.
[ (250 * Stern plan dist) - (175 * bow plan dist) ] is the deficit you need to work on. A weight Z placed Y inches from the center of bouyancy should balance things out. Z * Y should equal this deficit. You can experiment with different weigths and distances (lower weigth would require it to be placed farther toward the bow).
This would allow you to put the seats at the plan positions. But it may result in significant weights being required (which may or may not match what you actually want to carry). So, move the stern seat forward somewhat to lessen the amount of forward weight to carry or reduce the distance needed for the weight.
I suggest you take a level with you. Measure the "attitude" of the craft in the water when it's empty and work to match that attitude with you, your partner and any needed extra weight while on the water. For extra weight, consider just bringing a 5 gal water jug along and fill it with water from the river and move it around to see what you come up with. The most important thing is to ensure that when you're done, both paddlers feel like they are in a reasonable paddling position. You set the seats in a "reasonably comfortable positon" before you get near the water. You can also calculate what type of extra weight you will need and where to put it before entering the water. There is really less science involved here than I'm making it out to be.
I have a house on Lake Redstone a bit north of you. I've paddled the Wisconsin River past Arena many times. It's a wonderful resource. We should get together some time.
Re: Seat placement on my Freedom 17'9"
Ok, first off I can't believe the conditition the river is in. At the launch instead of there being water across all 300yards of river like in a normal year there's only about 100yards of actual river left! Back to the canoe...we clamped seats in place and I floated it with my friend who weights in at about 185. The bow seat is at about 44" and the stern seat is 55" from from center of bouyancy respectively. I don't have the exact measurements because I forgot to write them down however it seemed to be ok those locations. The only issue being we couldn't do much paddling because it was so tippy and for the lack of navigable water. Any reason I shouldn't go with what I discovered last night? Thanks
ruso
ruso