Maximum Beam

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Spring
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Joined: Wed Apr 05, 2017 6:28 pm

Maximum Beam

Post by Spring »

I am building the second of three 16' Prospectors and have had to stop to scratch my head. I learned a lot building the first.

With the second, I am a lot more pleased with how it looks overall. It is neat, and it is straight. What is different is that canoe 1 off the molds had an overall width less than the 34' of the molds. To correct that I simply installed a temporary thwart and carried on.

Canoe 2 is a full inch wider. When I look at the hull, it looks beautiful and I can see no obvious explanation for the difference in dimension.

As for dimension, I can see a number on the specs called Bmax. According to that, Bmax is 35". I have no idea what Bmax is, but I can tell you the interior dimension of my hull is 1" wider than the 34" station 0 mold.

I have asked Joan. She said the hull likely took moisture after the outer sheathing. It didn't. The climate is controlled. She also said I should use a thwart to pull it in to the station 0 dimension.

Canoecraft talks about the order of assembly. It says inwales, temporary thwart, decks et etc.

Therefore my questions are 2:

How big a deal is a 35" ID at station 0 if everything else looks OK?, and;

If I wanted to try to get the ID to 34", would using a temporary thwart to pull it in, rather than push it out as I did on canoe 1 be a reasonable thing to do?

My instinct is to install the inwales, then decide.


What say you?


Cheers!
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Jim Dodd
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Re: Maximum Beam

Post by Jim Dodd »

If you haven't glassed the inside, I'd try pull it in, and hold it in while I glassed the inside. As well as while the the resin cured for a week at least.
But in reality, 1" extra shear width is not a problem ! Especially on the Prospector. I'd go for putting the gunnels on.

A tightly tumblehomed solo, might be a different story.

My two cents !

Jim
Keep your paddle wet and your seat dry!
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Cruiser
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Re: Maximum Beam

Post by Cruiser »

I was amazed by how much I learned on the first boat, and the difference in attitude/confidence you then approach the next boat with.

The refrain around here is "show us pics" ... as that is worth a bucket of description. If I understand your question, you did the outer fiberglass and when you pulled the shell off the forms, the resting width (presumably measured shear to shear) was off a bit from boat to boat.

The thwarts (temp and permanent) job is to set that width and help stiffen/strengthen the gunnels. If you want to pin down what the width at that station should be, just measure shear to shear on that station and set the temp thwart width to hold the inside shear to shear measurement (at that station) to that width. You can do this temp thwart to pull the sides in by using small dadoes in the thwart or just a simple length to hold them apart .... you just figure out how you want it to hold the sides and cobble it together ( more than one location is a good idea).

You do need to have the temp thwarts in place during inside fiber glassing and gunnel installation, because those 2 steps will be setting the final canoe shape. Ideally when the permanent thwarts are installed they aren't actually shaping the boat very much, the other stages should have locked in about the right width.

Hopefully this isn't too far off track from what you were asking.

Brian
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Patricks Dad
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Re: Maximum Beam

Post by Patricks Dad »

I'm assuming you have the inside glass already in place....

Maximum Beam should be the widest measurement of station 0 (not necessarily at the sheerline). Beam at the gunnel is likely smaller (34"). Using a temp thwart to achieve that dimension is fine (which as noted should simply match the width of the station form at the sheerline). A piece of strip with notches a the right dimensions will do the trick.

You might look at where you are currently supporting the hull. If you pick up both ends, the beam will get wider. Balance it in the middle, the beam will be a bit narrower. Once gunwales are on, it will stiffen up. And thwarts will ensure correct final beam dimensions.

You're in good shape. Enjoy the rest of your build.
Randy Pfeifer
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Randy.Pfeifer1@gmail.com
Spring
Posts: 9
Joined: Wed Apr 05, 2017 6:28 pm

Re: Maximum Beam

Post by Spring »

Thank you all for your prompt responses. My computer gags if I try to upload pics. Ergo the lack thereof.

The bottom line is that the inner glass is on. The canoe is supported toward the ends. The 35" dimension is at the sheerline. I can find no reference either in Canoecraft or on the DVD to using a temporary thwart while glassing the interior to ensure a proper dimension, and so none was used. In fact I can't figure out how one would do it without it getting in the way.

My plan now is to do a number of things.

One is to accept some of the advice given here.

Two is I will support the canoe closer to the centre while I fit the inwales. Why not?

Three is I will temporarily fit both inwales, then check the dimension of the sheerline at station 0. It is remotely possible that the inwales will cause the hull to bow out slightly toward the bow and stern, and come in slightly at station 0. I'm not counting on it, but it is possible. It is also possible that the situation worsens.

Four is if need be, using a temporary thwart, I will see if I can bring it in, even if only slightly. What I will not do is risk introducing ugly curves to achieve a 34" dimension.

I am still puzzled as to how this occurred in the first place. I am building these using a stapleless method. I know I am dealing with a natural product here, and that it is normal for there to be some rebound as the hull is freed from the molds. Both hulls were built as identically as possible. Both have responded oppositely to coming off the molds. It was when I went to fit the temporary thwart I used on canoe 1 that I discovered the difference.

I hope to have a good day in the shop today. With luck I will have something further to report this evening. In the meantime, thank you once again for your input.


Cheers!
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Jim Dodd
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Re: Maximum Beam

Post by Jim Dodd »

How your hull was supported while glassing can make a big difference.
I move my saddles close so they squeeze the hull shape a little, while sanding and glassing.
I would try that as you dry fit your gunnels. I'm not guaranteeing it, but an option !
Time of year around here will make a difference, mostly with humidity.
Building in the Winter with dry heat, as compared to Summer humidity.
The planks you cut your strips, could also had different moisture levels.

It's good to analyse your work ! That's how you improve !

But again, and inch wider in the shear is not that big of a problem, on a tandem. You might even find it a benefit.

Spreading the shear in the middle, will reduce the rocker.
Just for fun, compare the rocker on your two canoes. As a tandem, the Prospector has plenty. A little less might actually be preferable.

Good luck ! OH pictures Are Required ! :wink

Jim
Keep your paddle wet and your seat dry!
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Cruiser
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Re: Maximum Beam

Post by Cruiser »

As Randy and Jim point out, the 1" needs to be put perspective .... it is in the minor category, you didn't even know it was wider until you measured and your eyes are about the best judge of the curves. With that small variation, pulling/pushing the shear an inch is not going to matter IMO.

To make a temp thwart, I just use a scrap 1x2 and put a 1/2" dado near one end, cut another dado at the right distance, at the other end. Use the sides of the second dado to get the spacing right, measure inside to inside (on the temp thwart) to push the beam, outside to outside to pull the beam ... hope that is clear. You could achieve the same thing attaching small blocks to the temp thwart as well.

I would use the temp thwarts when you install the inwales, you can always do a visual check from either end to make sure it looks good ...

When I support my boats I try and roughly divide the boat length in thirds and the supports go at the 2 lines that gives you.

As far as the boats being the same, well, the wood itself varies in each plank, there is no constant here. The material is changing, the amount of glue is varying a bit, the environment in a shop changes all the time, even the amount of resin absorbed can change with material, so having small differences in 2 builds is probably to be expected.

Brian
Spring
Posts: 9
Joined: Wed Apr 05, 2017 6:28 pm

Re: Maximum Beam

Post by Spring »

Still no joy with pics which is unfortunate. I'll sort that later. The good news is that as I indicated I temporarily fit both inwales to see what would happen.

Bottom line? Problem solved. As soon as I fit them I found that I am now looking at 34 1/4 inches, and the whole thing looks good.

In fact the 35" number went down by 1/4" just by moving the supports more toward the centre as suggested.

This may seem to some as much ado about nothing. However, when one has this much time and effort invested in getting the project this far, it is best to be cautious when it comes to things like this.

I'm going to putter with it more a little later on. I may glue up the inwales either today or tomorrow....after I stop happy dancing.

Once again everyone, thanks for your help.

BTB The idea of 3 canoes is that I have 3 daughters. These things should outlast me and so I think they make a nice keepsake that the girls will use.

One daughter lives in Cold Lake Alta. One lives in Revelstoke BC. I will deliver the first two canoes this summer. The 3rd daughter lives in Ottawa. I'll build her canoe over the coming winter.

Each canoe will come with a set of paddles that I'll carve, life jackets, ropes, and an emergency kit.


Cheers!
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Jim Dodd
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Location: Iowa

Re: Maximum Beam

Post by Jim Dodd »

I was soo involved with your hull problems, I forgot to extend a Welcome to the site !

Builders, are simply the best people in the World. At least in my book !

Again Welcome, and looking forward to more from you !

I use Photobucket to store, and share my pics. I'm sure there are others, even better ! It's just how I post pics !

Jim
Keep your paddle wet and your seat dry!
Spring
Posts: 9
Joined: Wed Apr 05, 2017 6:28 pm

Re: Maximum Beam

Post by Spring »

Thanks Jim.

I just came in from gluing up the second inwale. It seemed to go well. The beam measurement came out at 34 1/4". That's a win and a great relief.

Things should proceed smoothly from here. Thwart is next. Since I knew from the start I would be building 3 canoes, I made or bought shipsets of most things including thwarts.

The decks for all three used identical material and were glued up at the same time. I am hoping to have them completed and installed by the end of this week.

BTB. Under each bow deck, and out of sight is a hollowed out disk of Phillipine mahogany. The mahogany belonged to my dad, the girls' grandfather. Inside the disk is a commemorative coin, 3 the same. The coins were provided by my mother, the girls' grandmother.

Who knows what will happen to these canoes, or where they'll end up? For now though, sentmentality is being built into each one.

Cheers!
Spring
Posts: 9
Joined: Wed Apr 05, 2017 6:28 pm

Re: Maximum Beam

Post by Spring »

Canoes 1 and 2 have now been delivered to very happy daughters. Canoe 3 will follow this winter.

The first stop was Revelstoke BC. The second was Cold Lake Alberta. Both canoes were loaded onto specially built transport racks fitted to my Ford Ranger. By the Cold Lake drop that canoe had travelled almost 5000 km with no damage save for one mark on a gunwale. Considering the pounding they took on the way, I figure that was pretty good. Hopefully they'll get more marks on them, a sign of use.

The canoes attracted attention and generated conversation just about every time the Ranger came to a stop. It surprised me that they would generate that much interest. If I got waylaid by someone wanting to talk about canoes, my wife would just move off to the side and smile. She'd come back as soon as the conversation was over. We might be grabbing lunch at a restaurant, and we'd see people out in the parking lot inspecting the canoes. Like I said, I found it surprising they woud generate that much interest.

One thing I have learned is not to sweat the small stuff. If one is patient and careful, they can produce a very nice looking canoe where minor errors or inconsistencies are not evident.

As for me and what I think about building canoe 3 ? Put me in coach. I'm ready. No 3 will be the end of my canoe building. It has been great. I would recommend it to anyone. Canoes take a lot of time and space. I can use both to move on and do other things.

Cheers!
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Cruiser
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Re: Maximum Beam

Post by Cruiser »

I read somewhere that when you are tripping in a "built" canoe, to plan extra time at portages, I have found this to be a fair statement .... as you point out, it is also true just lugging them around.

I have also found that after the first/second/third canoe, my approach and skillset for building projects changed significantly for the better. I find myself using things I learned on other projects over and over.

After #3 is finished, don't be surprised if you get the urge to do a #4 ... the building process is quite addictive ... enjoy #3.



Brian
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Jim Dodd
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Re: Maximum Beam

Post by Jim Dodd »

After building 3 strippers. Think about helping others !
I have really enjoyed helping beginners, especially those within driving distance ! Not to mention the Great friends I've made along the way !
It's an art well worth sharing !

I hope you can share some pics with us !

Jim
Keep your paddle wet and your seat dry!
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