Portage Pram

[Bruce Bateau]

So the latest version of the pram comes with closed cell foam, with a plywood sandwich. There is an inwale (pictured), and a cap/top piece and a partial bottom piece yet to go on.


I'm not thrilled about this, but thought that perhaps it would be good to expand beyond my preconceived notions. That said, there are no instructions in the wacky manual to deal with this change.

Would you folks recommend that I fiberglass the whole thing together or just use a lot of epoxy to coat it all before painting?

-Bruce

[stromborg]

That's interesting, I wonder why they felt the need to add foam.

I think it wants some kind of protection but I'm not sure just a layer of fiberglass is going to do much.

[DBthal]

Bruce,

I also found the manual scattered and marginally useful.

Possibly the ply/foam sandwich is meant to add stiffness without adding weight. You mentioned a top & bottom cap yet to go on, however, are there additional pieces to support the oar sockets? I’d want to beef up those locations. Might be worth a call to Duckworks.

Dan

[Bruce Bateau]

That's interesting, I wonder why they felt the need to add foam.

I think it wants some kind of protection but I'm not sure just a layer of fiberglass is going to do much.

A friend told me that the original design sometimes had fractures at the bushings because there was a lot of pressure with minimal reinforcement there, but I'm not clear on the truth. .

[AJZimm]

Would you folks recommend that I fiberglass the whole thing together or just use a lot of epoxy to coat it all before painting?
-Bruce

Bruce, I don't own one so take my advice for what it's worth.

I suspect the boat doesn't need any glass to give it more strength, but that bottom panel is going to spend a lot of time on beaches. I would be inclined to epoxy on a layer of kevlar cloth just on the bottom panel. It's outrageously expensive and a bugger to cut, but that last property is what makes it extremely resistant to abrasion. I have added strips of the stuff to the centre line and bottom chines of my wood kayaks. The paint and epoxy may get worn through but the kevlar just gets a little fuzzy, and you can re-epoxy and paint it when it does.

[stromborg]

The bottom and first planks up the sides (on a flat bottom boat like this are they considered garboards or broads?) get a layer of glass. Bruce is wondering about the built-up gunnels and how to deal with the foam in the middle of the sandwich.

[Bruce Bateau]

Yes, Steve is correct. And Alex, there will be glass on the bottom, as well as some bronze runners on the skegs. One of the reasons I chose this design was because it was light enough to carry myself or even more easily with a partner. Hopefully that means less skidding- there's always some!

I am going to write to Duckworks today and I'll share their advice. They have been very responsive, though a bit surprised themselves at the changes to the kit. It seems that they are selling quite a few of these (or at least advertising them a lot); given that, it is surprising that there isn't a reasonably updated or even streamlined manual.

As Steve noted, it isn't super complicated to build, but a few things like the foam need guidance.

I stewed on this a bit last night. I think it would be really hard to encapsulate the whole gunwale in fiberglass without it looking like a big mess- and even then, I wonder if I would end up with a gap that could trap water. The bottom part of the plywood sandwich in the kit covers only the middle section of the gunwale, which makes me think the plywood is probably just to protect the foam from abrasion, not water. I plan to put the oarlock sockets into a pad like this:



-Bruce

[AJZimm]

Steve and Bruce,

I see I was too hasty in reading Bruce's post about asking for advice.

If I'm reading things correctly now, then "The bottom part of the plywood sandwich in the kit covers only the middle section of the gunwale" would actually make the gunwale at that point into a box section, which would add a lot more strength, in addition to abrasion protection

[DBthal]

Bruce,

The oar socket pad in your photo looks like a very good solution. You want to know that the attachment point is solid when you need to crank on the oars (wind or current).

Dan

[jpatrick]

I think I'd be tempted to cap that foam sandwich gunwale with a strip of wood. Wood would look nicer than fiberglass and be a lot more fun to do. It would likely not bend to that curve, so faceting might be in order. Gluing with epoxy will negate any strength loss by faceting.

Jeff

[stromborg]

I guess Poppy is now a Portage Pram 1.0

The OG gunnels are built up layers of ply, 4mm outwale, plank and inwale with (I think) 3 more layers of 4mm to pad out the area where the oarlocks go. The whole thing is a bit under 1 1/2" thick. There is enough "meat" to put the provided plastic bushings in tight to the inner face of the sheer plank. I did a fair amount of rowing in her last summer, mostly puttering around but I did do a few "speed trials" and everything held together. Doesn't take much to move her along but this is very much a lightweight flatbottom pram, every movement you make is going to have an effect. A short stroke seems to power her along much better than a long one (think dory stroke) we're not looking at a pulling boat here.

With all that out of the way...

The thing that I wonder about with the foam sandwich on Bruce's PP 2.0 is the concentrated point load around the oarlock sleeve. I would be tempted to figure out where the oars go, remove some of the foam in that spot and replace it with a chunk of wood so the bushings have something more solid to sit in. Maybe 6" long, glued between the plank and the existing plywood inwale. But I also don't know the density of the foam they sent along, it might be just fine?

[DBthal]

Steve,

The thing that I wonder about with the foam sandwich on Bruce's PP 2.0 is the concentrated point load around the oarlock sleeve. I would be tempted to figure out where the oars go, remove some of the foam in that spot and replace it with a chunk of wood so the bushings have something more solid to sit in.

That was my initial thought as well. If Bruce uses oar socket pads as shown in the photo above, it seems the bronze oar socket would take that point load.

Dan

[Bruce Bateau]

Drum roll please.....

Duckworks says that after the plywood is attached to all sides of the foam (using thickened epoxy) the gunwales should be wrapped in glass! And I quote, "ideally going from the inside of the hull, say an inch below the inwale, up and around the gunwale to the outside of the hull, again to around an inch below the gunwale."

Apparently this is the same as their new boat Scout, which has a lot of foam in it. See build thread here.

[DBthal]

Hmmm…

Fiberglass usually doesn’t like 90 degree sharp bends, so it seems like the gunnels will need to be quarter rounded and fillets applied where the hull & gunnels meet. Then there are the quarter knees at each end. Did they give any tips?

Did Duckworks say why they made the change?

[Bflat]

P1080041.jpgP1080045.jpgP1080044.jpg
I'm at the inwale stage of building my Portage Pram. The plywood caps as provided in the kit allow for zero error (no sufficient overlap) and so don't quite fit. I rectified that development by cutting my own caps from 4 mm ply with plenty of overlap to be trimmed after installation - problem solved. I now have those epoxied on and trimmed. The result is good and certainly adds a lot of stiffness to the form, especially considering that the design has no center thwart. I'm pleased. The bottom photo shows the ill-fitting kit part laid on top the cap I made.

I did put small (5" blocks) at the oarlock points within the built-up ply/foam inwale structure and anticipate no problems.

There are no bottom caps included in the kit I received, so I assume they're not intended or needed. As is, the ply cross section is kind of an "n" shape.

I figure that laying 4 oz. glass biaxially over sufficiently rounded corners will present little problem (that's worked for me before).

Bob

[DBthal]

Bruce & Bob,

I appreciate the updates and photos of your progress!

Dan

[Bruce Bateau]

Interesting idea on the wood blocks. Mine came with a partial bottom cap so I decided to just use it and leave the foam as is. I will add some oarlock pads. A friend and I wrapped the gunwales with fiberglass yesterday. It was a bit messy. We wetted out the wood and foam, then soaked the precut glass before stretching it out and putting it on.

So far it seems to be gripping OK. Fingers crossed that it holds.

[Bruce Bateau]

I've been away from the computer and the boat project for a few days, so here's an update.

Although the top and inside came out ok, there are lots of sags on the underside of the gunwale block, especially where the foam comes in contact with the glass.



I thought this would happen before I glued the foam on but figured the Duckworks folks were smarter than me, so I trusted. Admittedly, I'm not the world's greatest glasser, but I'm pretty disappointed.

I see a few ways forward:
a) cut out all the bad sections, turn the boat on its side and re-glass.
b) turn boat on side, slit the saggy sections open and pour a bunch of epoxy in there and call it good enough.
c) start over the way I wanted to and glue some laminated wood on there instead.

Any advice?

[AJZimm]

I've been away from the computer and the boat project for a few days, so here's an update.

Although the top and inside came out ok, there are lots of sags on the underside of the gunwale block, especially where the foam comes in contact with the glass.

I thought this would happen before I glued the foam on but figured the Duckworks folks were smarter than me, so I trusted. Admittedly, I'm not the world's greatest glasser, but I'm pretty disappointed.

I see a few ways forward:
a) cut out all the bad sections, turn the boat on its side and re-glass.
b) turn boat on side, slit the saggy sections open and pour a bunch of epoxy in there and call it good enough.
c) start over the way I wanted to and glue some laminated wood on there instead.

Any advice?

As I understand it, the glass on the underside serves a structural purpose, so I would go with either a or c, as I'm not sure you'd get the same strength with b.

[stromborg]

I think I'd go with "C"

[Andrew2]

I started reading this thread with interest and thought, great little boat . But the composite gunnels look a bit of an after thought and not a good one. While weight is important, I would use laminated wood. Maybe something light with a harder cap.

Very impressed by the efforts by Strom, Bruce and Dan.

[stromborg]

The original gunnel design is simply strips of plywood laminated to the sheer plank. After a summer of knocking about in the boat I am unsure what problem the new foam composite gunnel is solving.

[DBthal]

My 2 cents:

I would contact Josh Colvin and request good guidance from somebody at Duckworks or the designer. You shouldn’t be put in the position of trying to figure out how to work around a design modification without support.

Dan

[dbp1]

I was looking to see if there was another technique called out for the Scout (where they borrowed this from), and at least as done in these videos, doesn't seem like it... https://youtu.be/LBrrh3Okoms?t=1521 So not sure if they are going to suggest anything in particular...

[DBthal]

We can see in the video that the builder rounded the gunnel edges and put fillets where the gunnels meet the hull.

[DBthal]

Bruce & Bob,

Are there any updates? I’m sure it would help future Portage Pram builders.

[Bruce Bateau]

I took a little break on this to enjoy spring for a bit... and now back to the shop:

I didn't want to start all over, so I didn't remove the foam, figuring I could always do it later. I did remove all of the fiberglass from the inside of the top strakes, to the top of the inwale cap. I sanded down the wooden corners of the gunwale cap to make them a bit more rounded.

I then turned the boat on its side and coated the bottom of the foam with a layer of epoxy, added a generous fillet of thickened epoxy between the inside strake and the bottom of the foam. I wrapped several small pieces of fiberglass over the foam/wood inwale interface, just touching the fillet. I added more glass over any remaining rounded wood corners.

That seems to be holding and am now pretty much done with epoxy work.

The gunwales are a bit lumpy, but I think structurally sound. My friend Dan put it in perspective. He said that when he built his first dinghy, it was furniture grade. Then he parked it at the dinghy dock and every other boat beat up on it- scraped it, dinked it, etc. He said mine would get that way soon too and the best thing I could do was have a sturdy, non-cosmetic finish, which is where I'm headed.

I bought some Marshal's Cove marine paint in satin and am looking forward to getting it on the boat.

As noted above, if I was going to give any advice to future builders of this design, it would be to build up several strips of marine ply instead of the foam.

-Bruce

[Bruce Bateau]

I rounded up some lumber yard grade red cedar and am going to start working on some 6.5' oars to go with the pram. I'm going with the Pete Culler style. Varnish with some nice painted tips.

There are some nice step by step photos by Timeless Boatworks here.

-Bruce

[DBthal]

Thanks Bruce!

[DBthal]

Interesting article on the Portage Pram:

https://www.insidewaters.com/making-...thes-the-soul/

[Bruce Bateau]

FYI to future builders. I primed the boat this weekend. It took almost an entire quart!