altering plans
altering plans
After tons of research, I've decided that the White Guide design canoe in Gilpatrick's book is best suited for my needs, however, due to available building/storage space, I need to shorten it by a foot. Can anyone advise me on the best route to take in doing this? Move the stems in 6 inches each? Move all the stations in an equal distance? Can this even be done without messing up the lines and the handling characteristics?
Professionals built the Titanic; amatuers built the Ark!
spacing
If you reduce the spacing by a consistent amount everything will work out fine. For example, if there are 12 forms and you move each one 1" closer, that should work, but the bow and stern forms may need slight modification. Another option may be to remove the center form and keep the same spacing That way the bow and stern forms will not need any modification. Hope this helps.
Kurt
Kurt
A third option if the stations aren't plotted or cut out yet, is to loft the plans so that the boat is smaller in every dimension - whipping out the calculator, the amount of reduction for a 17.5 foot boat will be:
17.5/18.5 = 0.9459
So the plans will have to be reduced to 94.59% of the original, to get a 17.5 foot length, and a boat that is identical in every proportion to the original design.
To do this, the dimensions in the tables of heights and half-breadths will have to be converted from feet-inches-eighths, to metric, in millimeters. Then multiplied by 0.9459 and those reduced values plotted up on metric graph paper... they could be also be converted back to feet and inches,. and the lofting is done in the normal way.
17.5/18.5 = 0.9459
So the plans will have to be reduced to 94.59% of the original, to get a 17.5 foot length, and a boat that is identical in every proportion to the original design.
To do this, the dimensions in the tables of heights and half-breadths will have to be converted from feet-inches-eighths, to metric, in millimeters. Then multiplied by 0.9459 and those reduced values plotted up on metric graph paper... they could be also be converted back to feet and inches,. and the lofting is done in the normal way.
Thanks for the advice guys. Moving each station in equally to achieve a 12 reduction in length is probably best for this mathmatically challenged dude.
Rick..haven't cut out the plans yet. I am lofting them from a 2:1 scale plan in Gilpatrick's book. The plans are drawn on 1 inch graph paper that simply has to be lofted to 2" paper. Wouldn't there be a way to figure the reduction in the 2" square to say, a 1.8 or 1.94 inch square and achieve the same results as doing subtraction from a table of offsets? Does that even make sense?
Rick..haven't cut out the plans yet. I am lofting them from a 2:1 scale plan in Gilpatrick's book. The plans are drawn on 1 inch graph paper that simply has to be lofted to 2" paper. Wouldn't there be a way to figure the reduction in the 2" square to say, a 1.8 or 1.94 inch square and achieve the same results as doing subtraction from a table of offsets? Does that even make sense?
Professionals built the Titanic; amatuers built the Ark!
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Jim D
Rick has a good idea, you can save a ton of work by going to a good print shop, they can reduce, enlarge and print what you want!.. I've done this and it works, and only spent a few dollars!... The main thing in modifying plans is you need to fair the forms before you start stripping!.... By fairing , I take a strip and lay on the forms starting at the shearline and move the strip up the side and to the keel... I look to see if the forms are inline with each other as I hold the strip to the forms... I'm sure someone else can give a better discription of Fairing, but that's it for me!...Don't be afraid to experiment, as thats how we learn!.. Who knows you might be designing the perfect canoe!!!!... Good Luck
Great idea Jim. Let me make sure I have this straight...I can go ahead and loft the plans to full size. Then, take them to a print shop and have them reduced by 5.5% ( roughly). Then, do I still reduce the spacing of the stations by 1"? 17 inches apart instead of 18? I've never attempted anything like this so please forgive my ignorance.
Professionals built the Titanic; amatuers built the Ark!
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Todd Bradshaw
- Posts: 92
- Joined: Tue May 11, 2004 8:16 pm
Not to be contrary or anything....who moi?....but this whole process seems extremely poorly thought out to me. As has been shown numerous times throughout the last hundred years or more, over and over again by various conoe manufacturers, building various lengths of the same basic design almost always produces a series of boats which may share a profile or basic look, but which have very different in-use handling characteristics and capabilities. Old Town, for example has routinely built many of their models this way and they are indeed very different boats. The same is true with strippers like Hazen's 16', 17' 18' and 18.5' versions of the 34" beam Micmac model, even though they are built on the exact same forms just using different spacing.
If you did the homework and decided that the 18.5' White was the best design for your purposes, shortening it, especially by scaling it down, and then expecting it to share the speed, capacity, lift in waves, maneuverability, stability or any other paddling characteristics of the original boat is extremely unrealistic and probably not going to happen. It just doesn't work that way. You may end up with a decent, or even good canoe, but other than sharing the same stem profile, don't expect it to be the boat you thought you were building. It will be an experimental design which you may find to be a great boat, or not, and you may not know until it's finished which strikes me as a bit risky when there are plenty of excellent designs already available in the size range you want to build.
If you do decide to shrink one down, my suggestion would be to either loft enough of it out to get a look at some of the waterlines, buttock lines and diagonals to be sure the thing winds-up fair and resembles the original boat as much as possible, or to attach the stem forms and center form to the strongback and then position the other forms using strips as temporary battens to arrive at a fair shape with no surprises. Picking a random measurement and moving the forms closer together is asking for trouble and it usually strikes about halfway through the stripping process when you have expensive materials on the line. Shrinking by proportions also shrinks volume, capacity and stability and at a much higher proportion than the linear dimensions are reduced. It's one of the best ways to end up with an unpleasant surprise when you finally get the canoe in the water. If you are unaware of what kind of waterline beam and immersed volume you're looking for and need for the design to successfully work for your purposes it can be a good way to get into trouble.
I'm sure it's not what you want to hear, but if you want a White my suggestion would be to actually build one. If you want a 17'-17.5' canoe, I'd find one designed to be that size in the first place. It's a really bad feeling to spend a bunch of money and a couple hundred hours building a boat and then find that you don't like it when you finally get it in the water.
If you did the homework and decided that the 18.5' White was the best design for your purposes, shortening it, especially by scaling it down, and then expecting it to share the speed, capacity, lift in waves, maneuverability, stability or any other paddling characteristics of the original boat is extremely unrealistic and probably not going to happen. It just doesn't work that way. You may end up with a decent, or even good canoe, but other than sharing the same stem profile, don't expect it to be the boat you thought you were building. It will be an experimental design which you may find to be a great boat, or not, and you may not know until it's finished which strikes me as a bit risky when there are plenty of excellent designs already available in the size range you want to build.
If you do decide to shrink one down, my suggestion would be to either loft enough of it out to get a look at some of the waterlines, buttock lines and diagonals to be sure the thing winds-up fair and resembles the original boat as much as possible, or to attach the stem forms and center form to the strongback and then position the other forms using strips as temporary battens to arrive at a fair shape with no surprises. Picking a random measurement and moving the forms closer together is asking for trouble and it usually strikes about halfway through the stripping process when you have expensive materials on the line. Shrinking by proportions also shrinks volume, capacity and stability and at a much higher proportion than the linear dimensions are reduced. It's one of the best ways to end up with an unpleasant surprise when you finally get the canoe in the water. If you are unaware of what kind of waterline beam and immersed volume you're looking for and need for the design to successfully work for your purposes it can be a good way to get into trouble.
I'm sure it's not what you want to hear, but if you want a White my suggestion would be to actually build one. If you want a 17'-17.5' canoe, I'd find one designed to be that size in the first place. It's a really bad feeling to spend a bunch of money and a couple hundred hours building a boat and then find that you don't like it when you finally get it in the water.
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Jim D
Riverrat... I apologize if my post lead you away from building a perfectly good designed canoe!!.. It was merely meant to open your mind to other options!.. As Todd has explained, you would be better as a first timer to stick with the tried and proven design!!... Get some experience under your belt, and then become the new Gene Jensen! Good Luck!... Jim
Jim...no problem. I appreciate your input. It does provide some food for thought. It's kinda fun thinking thru all these variables and learning how one tweak here may affect an area over there. Thanks to all for your input. I'll just keep looking at designs.
Professionals built the Titanic; amatuers built the Ark!
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Dean in Eureka, CA
- Posts: 267
- Joined: Mon May 10, 2004 10:23 am
- Location: Eureka, CA
Kent,
I'm not getting up on top of my Redbird Soap Box, OK?
I just want to let Riverrat know that the Redbird is 17.5' long.
:
I'm not getting up on top of my Redbird Soap Box, OK?
I just want to let Riverrat know that the Redbird is 17.5' long.
:Everything will be OK[img::]http://www.mikenchell.com/forums/images ... uryi3b.gif[/img]
Dean in Eureka, CA
Dean in Eureka, CA
Dean,
I've looked at the Redbird. I've looked at the Redbird many, many times. Beautiful lines! I've also looked at the Nomad. These are the two designs Bear Mtn offers that I like the best. I think I may be trying to make function follow form. Can anyone compare the handling characteristics of the two?
I'm not an experienced paddler. I' ve only spent maybe 20 to 40 hours in a canoe my entire life. In fact, I'm so new at this I hardly know which questions to ask. The Canoecraft book says the RB is for experienced paddlers and talented novices. What makes it so difficult? The Nomad shows better stability on the chart on the web site. What makes it more stable?
I'm looking for a canoe that is in the 17 to 17 1/2 foot range, will not have to be "pushed" thru the water in flat, slow rivers and lakes like a barge, and will carry two men and their gear, yet can be used solo in a comfortable manner. I like the more traditional lines, i.e., the RB, the Nomad, the B.N. Morris and the Guide series.
I live in South Alabama. We have no white water here. I'll probably be solo 70 to 80% of the time, but ocassionally my son will be on day trips or two to three day camping/hunting/fishing trips with me. I'm 6'2" at 220, he is 6'1 at 240. We'll have our normal gear and if we're lucky, a nice whitetail. I have a hunting lease that gives me access to 75 or so "river miles" of shore line that I can camp and hunt on.
The thing that has steered me away from several designs is the description of a particular canoe being " unstable" or suited for experienced paddlers, or best paddled in the" leaned position"..those kinda things. Perhaps I should just build one I like the looks of that comes close to what I think I need and then adapt me to it rather than adapting it to me.
I've looked at the Redbird. I've looked at the Redbird many, many times. Beautiful lines! I've also looked at the Nomad. These are the two designs Bear Mtn offers that I like the best. I think I may be trying to make function follow form. Can anyone compare the handling characteristics of the two?
I'm not an experienced paddler. I' ve only spent maybe 20 to 40 hours in a canoe my entire life. In fact, I'm so new at this I hardly know which questions to ask. The Canoecraft book says the RB is for experienced paddlers and talented novices. What makes it so difficult? The Nomad shows better stability on the chart on the web site. What makes it more stable?
I'm looking for a canoe that is in the 17 to 17 1/2 foot range, will not have to be "pushed" thru the water in flat, slow rivers and lakes like a barge, and will carry two men and their gear, yet can be used solo in a comfortable manner. I like the more traditional lines, i.e., the RB, the Nomad, the B.N. Morris and the Guide series.
I live in South Alabama. We have no white water here. I'll probably be solo 70 to 80% of the time, but ocassionally my son will be on day trips or two to three day camping/hunting/fishing trips with me. I'm 6'2" at 220, he is 6'1 at 240. We'll have our normal gear and if we're lucky, a nice whitetail. I have a hunting lease that gives me access to 75 or so "river miles" of shore line that I can camp and hunt on.
The thing that has steered me away from several designs is the description of a particular canoe being " unstable" or suited for experienced paddlers, or best paddled in the" leaned position"..those kinda things. Perhaps I should just build one I like the looks of that comes close to what I think I need and then adapt me to it rather than adapting it to me.
Professionals built the Titanic; amatuers built the Ark!
Well, first let me say that I agree with Todd's caution that a reduced-size canoe will handle differently, and the safest option is to find another design. I suggested reducing the dimensions because this is less likely to create problems in construction than shortening in other ways.
Altering a design by rescaling has been done with good results elsewhere... at Northwest canoe, their Merlin was scaled up by 3.8% to create the larger 38 Special - both are excellent boats and receive favorable reviews by paddlers.
http://www.northwestcanoe.com/store/cat ... gory_id=26
The larger 38 Special was scaled up to accomodate the increased weight of larger paddlers... in the case of the White, scaling it down will reduce the load it can carry, and it will handle with the characteristics of a smaller boat.
Other designs, such as the Prospectors from Bear Mountain have also been scaled up or down, and the owners have generally been pleased with the results. In Canoecraft, Ted Moores states that the stations in his boats can be stretched from 12 to 14 inches without sacrificing the essential quality of the design.. the design can also be shortened by shrinking that distance. This is about a 15% difference, so I wouldn't see a 5% change as being too worrisome.
The bottom line is that a smaller or larger canoe will be a different boat from the original design. Whether that difference will be significant or not will depend on what it is subjected to, and the needs of the paddler, and if those needs aren't known from the outset, certainly the safest route is to go with a boat that was designed for that size.
My apologies iif this has created any confusion, but rescaling a design has been done often in the past and I didn't see why that option couldn't be included here.
PS.... Kent, your thought on adapting to the canoe rather than adapting the canoe itself is right on - some canoes will feel different at first, but the paddler will adapt quickly, and that canoe will feel normal with time, ole reliable. An 18.5 footer sounds like way too much canoe for the uses you described, and maybe 17.5 is still too large and difficult to paddle solo, but that's only my opinion, fwiw... 16 feet might be more like it for a mix of mostly solo & some tandem.
Altering a design by rescaling has been done with good results elsewhere... at Northwest canoe, their Merlin was scaled up by 3.8% to create the larger 38 Special - both are excellent boats and receive favorable reviews by paddlers.
http://www.northwestcanoe.com/store/cat ... gory_id=26
The larger 38 Special was scaled up to accomodate the increased weight of larger paddlers... in the case of the White, scaling it down will reduce the load it can carry, and it will handle with the characteristics of a smaller boat.
Other designs, such as the Prospectors from Bear Mountain have also been scaled up or down, and the owners have generally been pleased with the results. In Canoecraft, Ted Moores states that the stations in his boats can be stretched from 12 to 14 inches without sacrificing the essential quality of the design.. the design can also be shortened by shrinking that distance. This is about a 15% difference, so I wouldn't see a 5% change as being too worrisome.
The bottom line is that a smaller or larger canoe will be a different boat from the original design. Whether that difference will be significant or not will depend on what it is subjected to, and the needs of the paddler, and if those needs aren't known from the outset, certainly the safest route is to go with a boat that was designed for that size.
My apologies iif this has created any confusion, but rescaling a design has been done often in the past and I didn't see why that option couldn't be included here.
PS.... Kent, your thought on adapting to the canoe rather than adapting the canoe itself is right on - some canoes will feel different at first, but the paddler will adapt quickly, and that canoe will feel normal with time, ole reliable. An 18.5 footer sounds like way too much canoe for the uses you described, and maybe 17.5 is still too large and difficult to paddle solo, but that's only my opinion, fwiw... 16 feet might be more like it for a mix of mostly solo & some tandem.
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canoeblderinmt
- Posts: 415
- Joined: Sat Jul 03, 2004 12:04 pm
- Location: Butte, MT
About the Guide...
RiverRat,
as you know, until recently I owned a White 18.5 footer. It was my first canoe. LOVED it! After reading all the posts, and remembering having the Guide on the water, some thoughts:
1. Is there any place else you could build it? A neighbors, who might want to go halvsies, or become a paddling partner? It seems a shame to have to go to all this trouble for a 18 lousy inches.
2. The 18.5 Guide is fairly stable. I had it in some pretty good waves/wind crossing a lake and when we got her angled in she rode the waves that were a good foot taller than the bow just fine. She tracked pretty well, also. Having said that, she does require some initial balance. It's a bit like a bike. She will rock pretty easily, but secondary stability is great.
3. Given the weight considerations you anticipate; I don't know how big dear are in your part of the country, you might consider adding a strip or two to raise the sheer line. With me (215), my ex-girlfirend (a canoe-stealing 130), and two duffels of gear, there didn't seem to be a whole lot of canoe side left. Maybe I'm just a baby and worry too much, for she never took on water over the side, but it's a thought, especially if you are losing a foot and a half of length.
Some pics of my experience are here:
http://home.centurytel.net/schindler_ent/Canoe.htm
Good Luck,
Greg
PS: I wonder if we are the only Gilpatrick fans out there? Nobody else even mentions his name :?
as you know, until recently I owned a White 18.5 footer. It was my first canoe. LOVED it! After reading all the posts, and remembering having the Guide on the water, some thoughts:
1. Is there any place else you could build it? A neighbors, who might want to go halvsies, or become a paddling partner? It seems a shame to have to go to all this trouble for a 18 lousy inches.
2. The 18.5 Guide is fairly stable. I had it in some pretty good waves/wind crossing a lake and when we got her angled in she rode the waves that were a good foot taller than the bow just fine. She tracked pretty well, also. Having said that, she does require some initial balance. It's a bit like a bike. She will rock pretty easily, but secondary stability is great.
3. Given the weight considerations you anticipate; I don't know how big dear are in your part of the country, you might consider adding a strip or two to raise the sheer line. With me (215), my ex-girlfirend (a canoe-stealing 130), and two duffels of gear, there didn't seem to be a whole lot of canoe side left. Maybe I'm just a baby and worry too much, for she never took on water over the side, but it's a thought, especially if you are losing a foot and a half of length.
Some pics of my experience are here:
http://home.centurytel.net/schindler_ent/Canoe.htm
Good Luck,
Greg
PS: I wonder if we are the only Gilpatrick fans out there? Nobody else even mentions his name :?