ribs

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sue denim
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Location: South west France

ribs

Post by sue denim »

On the front cover of that very popular book there are two canoes . One has no ribs inside and the other has. I would like to construct the latter. Are these applied after a normal construction or are they in place as the boat is built?. Also what would be a preferable timber for these?.

If there is an alternative book describing this method then please let me know.

Regards Sue
willo
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Re: ribs

Post by willo »

There are few men that have the knowledge and skill to build that canoe , however there are ways of building with ribs that can be adopted to the epoxy method. Most canoe ribs are white cedar. Look at posts from Pattricks Dad here on the forum , he did a great job installing ribs after the hull was constructed. You can also look for books on wood and canvass construction, you replace the canvass with glass and epoxy for a similar look.
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Patricks Dad
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Re: ribs

Post by Patricks Dad »

Here's 1 link to a thread on this forum which shows a couple pictures of the Freedom 15 I built with ribs.

http://www.bearmountainboats.com/phpbb2 ... hilit=ribs

If you look in the Project directory for the Freedom 15, there may be a couple there too.

The "right" or traditional way of building boats with ribs called for bending the ribs over a full form first and the planking over that. I didn't want to take the time to build a whole form for just 1 boat (the form was traditionally used to make many boats), so I waited until I had the hull built and then installed the ribs after it was glassed (outside and inside).

Adding the ribs after the hull was built was straight forward but time consuming. I used Eastern White Cedar for the ribs. It steams and bends nicely (and was the wood of choice when building ribbed boats in the "old days". Once bent (using the hull itself as the form) I clamped them in place. I bent a 3 or 4 a night until I had them all bent. After they had all dried, I epoxied them in place and trimmed them to length to match the sheer line of the hull.

I love the result (but not the weight). I'd be happy to answer any questions about how I did it (but you may well come up with a better approach - have at it!).
Randy Pfeifer
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DSJ
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Re: ribs

Post by DSJ »

Why couldnt you strip a hull the usual way using waterproof glue, then remove the strongback, leaving the forms in place, then steam the ribs like Patrick's dad did.

Next step would be outer gunnels, then epoxy the ribs between the forms and finally remove the forms and install the remaining ribs.

The ribs should eliminate the need for any fiberglass, and the hull could be sealed with a coat of epoxy, then varnish.

My understanding is that the current cedar/epoxy method evolved using fiberglass to replace ribs, so it seems logical that if you put the ribs back, then the fiberglass cloth becomes unecessary.

I imagine this method could be used to construct a canvas covered canoe too.
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Glen Smith
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Re: ribs

Post by Glen Smith »

One problem with this method: the interior needs to be sanded before installing the ribs. Until you love hand-sanding in tight quarters.
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Patricks Dad
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Re: ribs

Post by Patricks Dad »

I would be reluctant to go with nothing on the outside (if that was your intent). The old style canoes had a layer of canvas over the outside of hull (as you note - today replaced with glass/epoxy). So, I glassed the outside before I pulled it off the forms (the usual technique). I did put a layer of 4 oz glass on the inside (probably overkill but would have put a couple coats of epoxy on this inside anyway). As Glen notes, the inside was easy to sand with all of the forms out. I did use the forms (modified) as a jig to hold the ribs in place while the epoxy set.
Randy Pfeifer
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DSJ
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Re: ribs

Post by DSJ »

I'm pretty sure Sue was referring to the photo onthe cover of Canoecraft.
I think that canoe would have been built with methods that pre-date canvas covered construction.
Imagine trying to get a water tight craft just by nailing planks to ribs!

Chapter 2 of Canoecraft is a good read for a general description of some of the old methods used.

Sanding between the forms wouldnt be fun, but it would be do-able, much like Charger's current Adirondak Guide boat build.
willo
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Re: ribs

Post by willo »

There are some buildars like Langford that build the canvas style canoe and cover it with glass on the outside and no glass on the inside. The strips are wide as they would be for building a cavas canoe and likely not bead + cove. Wider strips would make sanding much easier since there would be a lot fewer joints. I have always wanted to try it myself , some day. The canoe on the cover of CanoeCraft was built a long time before epoxy was invented. It was made with such precision that only spar varnish keeps it sealed. You need to see one of these old beuties up close to really appreciate that lost craftmanship. Langford has a website , check out the pics of their canoes , look at the price and go build your own
alick burt
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Re: ribs

Post by alick burt »

The nearest thing i have seen yet to a description of how to build a canoe with ribs like this is in a lovely book called The Canoe a Living Tradition by John Jennings.isbn 1-55407-080-5.
on pages 190 to 193 Walter Dean along with helpers(Ted Moores,Ron Squires and Fred Forster) constructs a wide board and batten basswood canoe.
Maybe this type of form ribs and stems could be used in conjunction with thin cedar strips to produce a boat like the one on the front of canoe craft.perhaps with epoxy used to glue the strips a more water tight hull could result but I still think an outer layer of cloth and epoxy would be a good idea to provide extra strength and durability.
Im just a cabinetmaker but i like to keep an open mind on these things!
The book is great reading too in all the other chapters.
regards
Alick Burt
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Glen Smith
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Re: ribs

Post by Glen Smith »

on pages 190 to 193 Walter Dean along with helpers
That would be Walter Walker and not Walter Dean.
alick burt
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Re: ribs

Post by alick burt »

oops sorry my mistake
I Apologize.
regards
Alick
sue denim
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Re: ribs

Post by sue denim »

Ok here goes.

I am not new to woodwork as it is my job.

I have put some thought into the canoe with ribs issue and have come up with the following idea.

It is a little long winded but I think it will work.

Create a form in the usual way, then cut about 7mm off each mould and replace with a sacrificial piece of wood. Manufacture wood strip as per normal. Take it off the mould, sand and epoxy internals. Remove 7mm sacrificial timber and replace with 8mm thick ribs. Put wood strip back onto moulds. Sand exterior. Using those delightful little copper nails, nail through into ribs (not every plank and not right through at this stage).
Then remove from mould and clench over points as per original.

Epoxy exterior.

I am going to make a straight forward wood strip before trying this, but I am certain it can be done this way.

Your thoughts please.
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Patricks Dad
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Re: ribs

Post by Patricks Dad »

Sorry but I'm not following you:
Create a form in the usual way, then cut about 7mm off each mould and replace with a sacrificial piece of wood. Manufacture wood strip as per normal. Take it off the mould, sand and epoxy internals. Remove 7mm sacrificial timber and replace with 8mm thick ribs.
Creating the form in the "usual way" would mean (to me) one cross-section per foot.

"Remove 7mm sacrificial timber and replace with 8mm thick ribs" would allow for a single rib per form (1 per foot). Ribs need to be much more frequent than this.

I think the "right" way to do this would be to build a real form that is continuous rather than 1 foot cross-sections and then apply ribs in the traditional way, fair them, and then strip.

maybe that was your intent all along...
Randy Pfeifer
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Patricks Dad
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Re: ribs

Post by Patricks Dad »

Here's a jig I used to glue ribs into the Freedom 15. Each form was used for multiple ribs (in areas where the hull cross-section is larger than the origianl form). Note that the ribs, in general are not all perpendicular to the baseline. Some of them (near the bow and stern) have a more compound shape to them to best follow the shape of the hull. So the jig needed to be leaned forward or backward.

Image

The primary drawback of this approach is that the outside surface of the ribs (the surface that contacts the hull) can't be "faired" easily (as you would be able to do by putting the ribs over a full form before planking. To address this, I squeezed thickened epoxy into any gaps that resulted.
Randy Pfeifer
(847) 341-0618
Randy.Pfeifer1@gmail.com
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