A Raven from Scratch

[Gamma1214]

Coming soon to a garage near me... Round 2 starts next week. This time I'll be looking for a bit more maneuverability in moving water and, as this boat is destined to ply some waters favored by Memaquay, it seemed fitting to trust his judgement and build his preferred hull.




This time, I'll be building a Raven; a John Winters design that I purchased from Martin Stepp at Green Valley Boat Works. The hull will be Tamarac (aka Eastern Larch locally) with Sassafras trim. To offset the heavier weight of Larch (37 lbs/cubic foot) compared to Western Red Cedar (23lbs/cubic foot), I'll, again, be building with 3/16 in strips instead of the traditional 1/4 inch. As this (37lbs x .75 = 27.75 / cu ft equivalent) still leaves me about 20% heavier than the Cedar, I'll be seeking ways to lighten the build and I hope to finish out at or below 50 lbs. (This is a deeper hull than my Freedom Solo which tipped the scales at 45 lbs so I'm prepared to miss the weight goal).

One thing that I neglected to do last time was to keep track of the hours and total cost of the build. I'm unsure I can detail total cost as I still have a gallon(ish) of epoxy left from the Freedom but I hope to be able to punch the clock a little more diligently and track the time investment a bit more closely.

I've got a ton of commitments demanding time and attention through the weekend but I should be milling strips on or before Feb 1st with a tentative (Canadian) launch date of June 30th (it won't break my heart to test it locally prior to that).

 

[memaquay]

I'm sure tamarac will look beautiful, probably nicer than red cedar even, but I would still be concerned about the resinous nature of the wood. Plus, the Raven is naturally a heavy canoe. I have never seen anyone build a stripper with tamarac, the results should be quite interesting. Looking forward to seeing it taking shape!

 

[Gamma1214]

You've expressed concern about the resin before. I'm not a woodworker and, perhaps, someone else is as obtuse as I so I have to ask: Is the concern because the resin in the wood will gunk up the sandpaper and making sanding a PIA (I'm not planning to do a lot of sanding) or that it may cause bonding issues w/ the epoxy? If the latter, is there another resin (polyester?) that might penetrate to wood more easily and give a better bond?

 

[Alan Gage]

I have no idea how resinous Tamarac is, I've never used it. But, as far as sanding goes, if the wood has been kiln dried and heat treated it shouldn't pose a problem. If it has not been heat treated it might not be sandable.

Heat treating wood in a kiln not only kills any bugs that might be living in it but also 'sets' the pitch by boiling away the lower temperature compounds. So if a wood has been heat treated to 160 degrees then the resin, pitch, sap, or whatever you want to call it should remain solid and hard up to that temperature. If the temperature of the wood is increased to 190 degrees then it may become soft and gummy again.

I have personal experience with non-heat treated red pine and spruce. This wood would normally sand fine if purchased from a lumber yard because it would have been heat treated in a kiln. But only being air dried after coming off my sawmill makes it impossible to sand. The surface feels dry and non-tacky but as soon as the wood is touched with sandpaper it gums it up and as soon as it's run through the planer the freshly exposed surface smells strongly of pine resin and has a slight tackiness to it. I can't imaging trying to sand a canoe hull made from that wood.

I'm not saying tamarac is going to have the same problems but it might be something to take into consideration. I'd probably take one of those tamarac boards and attempt to sand it and see what happens. Then I'd apply some fiberglass and epoxy to that freshly sanded surface and try to pull it off after it's cured just to be sure.

Alan

 

[Gamma1214]

Thanks Alan, that's great info. The Larch is air dried so I'll swing over tonight & glue up a test panel or two. I've also got a few hundred feet of white pine coming as payment for off-loading at the sawmill so that will have to be taken to a kiln before I use it on the next one. I guess, to be safe, the Slippery Elm should be cooked also.

 

[Alan Gage]

Thanks Alan, that's great info. The Larch is air dried so I'll swing over tonight & glue up a test panel or two. I've also got a few hundred feet of white pine coming as payment for off-loading at the sawmill so that will have to be taken to a kiln before I use it on the next one. I guess, to be safe, the Slippery Elm should be cooked also.

Most hardwoods don't have pitch like softwoods do. I use a lot of air dried oak, ash, walnut, elm, basswood, and willow and have no problems with any of them.

That's not to say that kiln drying isn't still a good idea. It will ensure the wood is dry and stable and will kill any bugs living in it. More than once I've had bugs hatch from my air dried ash after it's been turned into flooring or furniture.

Alan

 

[Cruiser]

Gamma, I know you mentioned you have some epoxy left from the previous build, but I will share some info on my epoxy plans for the next build, may be of interest, since you haven't started yet.

I have built a few boats now and I find people who start with a particular epoxy are more inclined to stay with that epoxy. I started with 5:1 East System Epoxy , which is about the same as most of the other 5:1 epoxies out there (Total Boat, West, MAS) .... yes, there are differences or claimed differences, but the general operational parameters are the same.

The biggest limiter IMO is the recoat requirements ... you really need to time the additional coats to get the chemical bond and avoid the sanding between coats. This is not a deal breaker, just a PITA, making for a very long day of glassing to avoid missing the chemical bond time,

When I started to plan this next build I was researching epoxies for use with S glass, something better than the 5:1 that is my go to ... something to give a clear finish on a glass cloth reputed to be harder to wet out. That led me to this link from Laughing Loon : https://laughingloon.com/epoxy.html I have posted it before, but has changed the way I look at the glassing operation. I encourage you to read it or reread if already have ( I posted it before).

I plan on using a 2:1 System 3 SilverTip Resin (Thinner) and the General Purpose (Bit thicker) . Recoat time is 72 hours, cure time is 72 hours .... that changes the entire game of glassing when compared to a 5:1 epoxy.

Using a seal coat with a 5:1 is pretty much a non starter for me, you can't wait for a tack free finish or you have to sand .... use the System 3 and you just do it the day before and it is dry to put the glass on and available for recoat. The advantage is simple, the seal coat can be applied lightly (you don't need to saturate the wood) and you don't need to worry about starving the glass ... next day the wood is already sealed, so you are just wetting out the glass, done carefully this should be simpler than bare wood, you don't have to worry about starved glass. If it is getting late, you can safely push of coating to the next day and still have a chemical bond.

I will be trying the seal coat this time, because using a light seal coat means the wood doesn't need to get saturated and the the only epoxy used applying the glass, will be that required to wetout the glass, potentially saving significant weight.

I also think the recoat regime of 72 hours is going to make using the epoxy a lot more flexible.

The Loon link also has a lot of good advice IMO.

Looking forward to seeing you make some sawdust.


Brian

 

[memaquay]

Yup, what they said, lol. System three has been my go to for years. Clear coat is even better than Silver tip for wetting out, it is thin, like water. My problem with tamarac is it takes a really long time to dry (I have cut it and used it for firewood), and it is a really squirrely wood, boards dry all crooked. It is also tough to work with, weighs a ton, and is very resinous, to the point that I would be worried about epoxy adhesion. However, it is beautiful, so hopefully your test panels will be positive.

 

[Jim Dodd]

Some good advise so far.

Polyester resin, will not bond as good as Epoxy.

The S-glass I have used from Sweets
Sweets composites Is just as easy to work as E-glass. It is very slightly more visible, but you have to get very close to notice the difference.
A Hull built with S-glass.

 

[Roybrew]

Great! Another Raven, I look forward to following along on this one.
What stem type are you going to use?

You mentioned the depth, I didn't realize how deep it was until I started planning how to install my seat. It is 1 inch deeper then my tandem 16' Wabnaki.

At the speed I'm going, you'll have yours done before first.
Roy

 

[Gamma1214]

I'll be using s-glass on the exterior (figuring 1 layer of 4 oz) but I'll likely get it from US Composites as I did last time. I used both s-glass & e-glass on the first and I can't see any difference. Inside will be 4 oz e-glass.

I glued up a test panel last night (just edge glued as I didn't have the shaper ready). The test panel experimenting will set me back a week but seems well worth it. I'll sand it, glass it, allow it to sit 3 or 4 days and then break it. If it goes well, I should be beading & coving strips next Sunday. I'm far more worried about epoxy penetration than the sanding part. I didn't sand much on the last one & I'm not figuring on doing much on this one either. I'm planning to just knock off the high spots and allow the epoxy to self-level. (should look like glass )

@Roybrew : "Stems"?... what are stems? This will be a Raven on a diet so I'm going to try and shave a few pounds off the start and build this stemless. Mem may not approve but I hit some of his rocks (fairly hard considering the low water level) with the stemless Freedom last fall and it held up.

 

[Cruiser]

I'll be using s-glass on the exterior (figuring 1 layer of 4 oz) but I'll likely get it from US Composites as I did last time. I used both s-glass & e-glass on the first and I can't see any difference. Inside will be 4 oz e-glass.

I glued up a test panel last night (just edge glued as I didn't have the shaper ready). The test panel experimenting will set me back a week but seems well worth it. I'll sand it, glass it, allow it to sit 3 or 4 days and then break it. If it goes well, I should be beading & coving strips next Sunday. I'm far more worried about epoxy penetration than the sanding part. I didn't sand much on the last one & I'm not figuring on doing much on this one either. I'm planning to just knock off the high spots and allow the epoxy to self-level. (should look like glass )

@Roybrew : "Stems"?... what are stems? This will be a Raven on a diet so I'm going to try and shave a few pounds off the start and build this stemless. Mem may not approve but I hit some of his rocks (fairly hard considering the low water level) with the stemless Freedom last fall and it held up.

Maybe make 2 panels Gamma, I think it may be stronger with the S glass on the interior, not exterior

 

[dogbrain]

I'll just comment that I would definitely use s-glass on the exterior for abrasion resistance. I agree that using it on the interior would increase hull stiffness by some amount, not sure how much. On my last 4 boats I used 4 oz e-glass inside and out plus an additional layer of 4oz s-glass on the outside football. With 3/16" strips this is about as light as I would ever build a strip boat intended to be used for tripping. From the pictures of the plans, the Raven looks like a rounder hull than other designs, so maybe you could get away with just the one layer on each side. Build it and see, you can always add another layer if the hull isn't stiff enough. How about s-glass inside and out?

Mark

 

[Jim Dodd]

Just spent a little time, looking at US Composite's 4 oz S-glass.
The widest they carry is 30".
That means a seam, down the keel.
That's OK, but Sweets carries 60" width, for $3.00 more per yard coverage.
The extra time and work involved, glassing the outside. I'd lean towards the Sweets 60" S-glass.

 

[Cruiser]

I'll just comment that I would definitely use s-glass on the exterior for abrasion resistance. I agree that using it on the interior would increase hull stiffness by some amount, not sure how much. On my last 4 boats I used 4 oz e-glass inside and out plus an additional layer of 4oz s-glass on the outside football. With 3/16" strips this is about as light as I would ever build a strip boat intended to be used for tripping. From the pictures of the plans, the Raven looks like a rounder hull than other designs, so maybe you could get away with just the one layer on each side. Build it and see, you can always add another layer if the hull isn't stiff enough. How about s-glass inside and out?

Mark

No argument that S glass has more abrasion resistance, however, S glass is some 40% stronger under tension and both E glass and S glass are comparable in compression (exterior layer under impact). If we are talking impacts from the outside, which is likely the case ... the decision is basically, am I worried about abrasion or the ability of the hull to withstand the impact.

If the S glass is placed on the inside, it is not a matter of stiffness, but a significant gain impact resistance ... if placed on the outside, it has better abrasion resistance, but the strength of E glass.

You do need to build to your own personal usage habits, but using one layer of S glass on the exterior is just a waste of the 40% additional strength you bought (which isn't cheap), might be better to just put a graphite abrasion epoxy coating on the exterior and call it a day.

If there can only be 1 layer of S glass ... I really stand by the idea that it would be best used in the interior. Abrasions aren't too bad to fix, but a busted hull is a whole different story.


Brian

 

[Cruiser]

Just spent a little time, looking at US Composite's 4 oz S-glass.
The widest they carry is 30".
That means a seam, down the keel.
That's OK, but Sweets carries 60" width, for $3.00 more per yard coverage.
The extra time and work involved, glassing the outside. I'd lean towards the Sweets 60" S-glass.

I got my 60" S glass from Sweets, haven't even opened it yet, but I did notice that when you order pay attention to the quantity discounts ... I ordered 3 extra yards and it was cheaper than what I was originally going to order, because I crossed one of the limits for discount.

I think if I was doing 30" cloth in this case, I would be tempted to just run it side to side with a 2" overlap ... sort of a little rib of extra strength every width ... of course, if I only have 1 layer of S glass, I am firmly in the "use it on the inside house" .... I am also leaning to DBs final comment of consider both layers in S glass

 

[Gamma1214]

I'm not married to a single layer but we'll see. My last was 4 oz e-glass inside & out w/ a layer of 6 oz s-glass on the football so the 30" s-glass was perfect. I did my inside glass side-to-side w/ an overlap so 30" is perfect in there as well.

I picked up the test panel tonight & hit it w/ a rasp to level it somewhat. I didn't have a lot of time to sand it but preliminary results seem positive. I'll try to finish sanding it & glass it (w/ something... probably leftover scraps) on Wed.

 

[memaquay]

I have no experience with S glass, but have lots of experience with destroying strippers. Many of my boats were used by the school club, so beat around pretty hard by teenagers. In the worst of conditions, I only ever had minor issues with the outside hull. A few times, some kind of abuse might go through the glass to the wood, but usually in small sections that could be taped until we got back and then easily repaired.

The only catastrophic failure that I had was on the inside hull. I had built the J. Winter's Winisk, a fairly large canoe, 18.5 feet long. This was when I was still building with only one layer inside and out. I was on the Steel river, and a new log jam had formed in an area with very steep cliffs. Got the canoe in the water at the end of the new port, and jumped into it, not realizing that there was the butt end of a log under the hull. The inside glass split in the middle of the canoe, length wise for almost 24 inches. The only thing holding the hull together was a thin layer of six inch glass on the outside hull. With another 8 hours on the river and a couple of hours across a big lake I was fairly paranoid that the outside would split too. However, we were able to limp out. I did manage to repair the canoe, but it was an important lesson in structural dynamics.

I'm not sure how much weight you will save using the S glass, but I think it will be a waste on the outside. The inside is the most vulnerable to catastrophic failure. If the goal is to save weight, I would say substituting cedar for planking would be the most probable solution.

My first Raven, built of white pine, had six ounce eglass inside and out, and a four ounce football on the outside. One would think it to be practically impossible to destroy, and yet I had a similar split, although only about three inches long, on the inside hull after hitting and lodging on a rock at full speed. That thing was a beast to carry, and as i got older, I reached a point where it was just no fun to throw that thing around anymore (traded it to Jonathon Kelly for a hammock, which I still haven't used, lol, but that raven appears in some of his videos).
And so from my long winded musings, I have realized i am really trying to say a couple of things:

Is the cost of Sglass justified in real world performance?

If weight is a real concern, ditch the tamarac, get some cedar, and really minimize trim. Gunwales, decks and all that jazz can turn a light hull into a beast.

However, if you do build in tamarac, I'm sure you will hold the distinction of being the first person to ever do so, and if your tamarac is anything like ours up here, you will have a beautiful looking hull. Plus if you get stranded, and get hypothermia, that tamarac hull will burn hotter than Satan's arse.

 

[Gamma1214]

Thanks Mem, your musings are helpful. I have a lot of leftover 60" e-glass so maybe one layer of that on the outside w/ bias strips of s-glass on the high wear areas. Given your structural failures, I'm thinking 30" s-glass sideways on the inside w/ an extra layer in the football.

If the epoxy bonds well to the Tamarac, I'll pay the weight penalty and build with it. It's just too pretty NOT to and I'm figuring minimal trim like the last one (and I've got another idea to cut weight dramatically).

Here's the test panel. I deliberately used some sapwood (lighter) and some heartwood for this but I may not mix both or may just minimize the sapwood when I build

 

[Cruiser]

Sometimes it is better to take a step back and really think about what you want from the boat.

If you want to save weight and want to use Tamarack, those things aren't necessarily mutually exclusive ... a nice white cedar hull with a 3"-5" Tamarack band just above the water line would likely look pretty good ... maybe tamarack decks. If you aren't stuck on a Tamarack hull, maybe consider it as the accent, not the main, sometimes less is more.

If you start adding extra layers of glass here and there, that you didn't initially plan ... starts piling up a lot weight fast. If you have to carry that boat any distance, that extra weight becomes a chore real fast.

Brian