An extra trippy Merlin.

As part of my plans, I'll need to be able to tilt this hull (before glassing the exterior) 90 degrees or so (side-to-side) and I lack the space to tilt the strongback as Jim does so I needed to devise something that would allow me to rotate it in place. I also wanted to make it removable as every hull is unlikely to get this treatment so a stationary SB is still likely to be ok under normal circumstances.

With 3/4 inch plywood forming the SB and 1/2" OSB above, I endeavored to find the center of balance and theorized that it would not be too far below the top of the SB. I measured & marked the center of the beam and screwed on a flange that will accept 3/4 inch black iron pipe.



Then, staying somewhat true to my automotive background, I grabbed a couple of 6 ton jackstands, removed the rams and replaced them with some 5/4 x 1 3/4 inch scraps (Sassafras left over from paddle making in this case but anything would work). I marked and cut out a notch in the top



inserted them in the jack stands, lifted them (slightly) off of the floor and installed a couple of screws to act as stops so that the weight of the SB would be transferred to the base of the jack stands. I also used some paddle scraps to act as wedges to secure the new rams



I traced the footprint of the SB with sharpie so that I could land it in the same spot, inserted 6 inch pipe nipples into each flange...



and lifted the SB onto the improvised jack stands. I'll need to tweak a little to better center the weight on the jack stand base (as it stands, the pivot is almost wide of the edge of the base and that's a bit precarious IMO) but I'm very pleased that the experiment went as well as it did on the first try and that, with about 3 inches of lift, I did not need to remove the feet from the SB



The SB rotated easily in place with enough room to walk around it on both sides and, when lowered back onto the floor, I rechecked and everything was still level & plumb.

I'll adjust the jack stand arrangement tomorrow to keep it centered and I should be ready to start stripping. With one week until enforced social distancing during radiation treatment, I'm very hopeful that I'll be ready to glass this hull by March 5th when I'm, again, cleared for human contact.

The reason that I need this rotation will, hopefully, be evident at that time.

By the looks of your stand, you need just as much space,as simply tilting your strong back.

Adding some weight to the legs to offset the weight of the forms and strips.
Looks like you are getting there.

Good luck with your Radiation Treatment !

Jim

I am seeing a triangular support on the ends, with that nipple at the apex, in fact if you want to get around the back and forth weakness, maybe some more like a large version of a painters Pyramid

That wouldn't use much material and should give solid end support.

I stopped over briefly tonight, primarily to fix the jack stand set-up.

By the looks of your stand, you need just as much space,as simply tilting your strong back.

Click to expand...

No, when I tilted it without lifting the base off of the ground, the hull was resting on the infeed table. By using the pipe nipples, I've moved the point of rotation from the floor to the top of the strongback and I can walk between the infeed table and the top of the forms.

I am seeing a triangular support on the ends, with that nipple at the apex, in fact if you want to get around the back and forth weakness, maybe some more like a large version of a painters Pyramid

Click to expand...

I can see how that would work but I think the jack stands will work for the task at hand. I expect that the hull will only need to be supported as a rotational assembly for an hour or two, I probably won't rotate past 45 degrees and I'll have a support mid-hull to further stabilize it.

Good luck with your Radiation Treatment !

Click to expand...

Thanks Jim. I'm not at all worried but I appreciate it nonetheless.

OK... I really didn't like the position of the point of rotation in my last picture above. The weight was borne by the ram almost directly above the outside edge of the stand base and (as anyone here can attest, getting the weight too far outside of the edge of a rotationally-capable assembly can be catastrophic).

I was seeing two problems: 1st, the ram could move too freely in the base and the top of the stand did not have enough surface area to stabilize it and 2nd, the wedge made the situation worse by encouraging the ram to tilt as it passed through the top of the stand.

I solved it by taking some scraps of OSB, cutting them into 6 1/2x 8 inch rectangles & fitting them into the bottom of the jack stand. I then inserted the ram, measured the distance from the top of the stand to the screws I'd installed previously & cut the corresponding length off of the bottom of the ram. A single screw through the OSB and into the bottom of the ram stabilized the set-up a lot and the wedge now tightened the ram without forcing it out of alignment.



I placed the SB onto the revised stands and I am very confident that this will do.



I did put one strip on around the sheer but I'm undecided about whether to fix or shim that station... I guess that will be an in-game decision sometime next week as I've got tons of crap to get done before Wednesday.

It's also really weird looking at these forms after building the Raven. This boat looks tiny by comparison and (especially as the Raven turned out well and the stations were true) I was tempted to reinstall the Raven forms and just build another (but I won't... at least not yet...)

I'm now radioactive (they actually gave me a wallet card & warned me that airports & tunnels could detect me... What the Hell did I swallow?!) and, as I need to avoid people for 4-5 days (I know, tragic, right?), I wandered over to the boat shop.

First order of business was to fix the errant form. I was really tempted to take all of the forms down & build another Raven (I like the looks of that hull) but, in the end, I figured that fixing the forms was good practice and the thread's too old to change the title...

I, therefore, marked the undersized form at 1 inch intervals from the top of the strongback, marked the adjacent forms at the same interval and, using a short(ish) strip, measured to see how far off it was at each strip.



I marked the measurements on the undersized form then removed it & transferred the measurements to a leftover piece of OSB (I had enough left over to make 2 forms or screw this one up & try again).



I cut it out with the bandsaw, sanded down to the lines & test fit it. I sanded a little more, here & there, until I was satisfied that it was as close as I could get it (given my patience and ability) and screwed the revised form into place.



One other change that I've made for this build (ok, two changes)... I've switched from Gorilla Wood Glue to Titebond II as I can buy it in gallons for about $27 (US) so it's considerably cheaper than the Gorilla. I've also decided to ditch the syringe this time as it's been kind of a PIA to refill it 3-4 times for every lap around the hull.

Instead, I took a mostly empty bottle of Elmer's Glue-all, washed it out and poured the Titebond into it



I'm reasonably optimistic that I can get a thin bead with it but, realistically, I want a little more squeeze-out on this one anyway as I'd rather cleanup glue on the inside of this hull than have gaps between the strips (the reason for this will, hopefully, be clear by the middle of next week)

In the end, I fixed the forms & got the first 3 strips on today. I'm hoping to be sanding by the end of my quarantine on Sunday & I think I've got a decent chance at it.

Well, I'm certainly not sanding anything tomorrow. In fact, I'm probably back to square one tomorrow morning (unless someone here can pull a rabbit out of the hat)

I was making good progress and was about 1/2 done with stripping but the strips were starting to oil can between the forms.



I'd had that happen in small areas of other builds and was able to work them out, usually by bracing the pushed-in area against the strongback before glassing. In this case, however, I was nowhere near the bottom of the hull and the further I went, trying to force the strips into position, the worse it got until it was ridiculously bad.



At that point, I decided that it must have something to do with the grain of the strips. In order to remove all strips showing deformity, I wound up removing 4 strips. (note: one hazard of building stemless: If you need to remove any strips, you'll have to do both sides because of how they interlock at the stems)

I carefully cut along the glue joint with a razor knife, cleaned up the edge of the 1st un-deformed strip and reshaped the cove using a 1/4 inch chainsaw file. I carefully selected strips that seemed to have a predisposition to bending in the direction they'd need to and started stripping again. This worked better but there is a slight oil canning happening and I'm sure it will continue to get worse as I go up.

My options at this point:
1) I can make a series of relief cuts in the strips as needed to collapse the bulge then add a drop of glue to the relief cut.



This will work but every strip will need to be relieved and I suspect that more cuts will be required as I continue up (at least until I reach the football area). I also suspect that I'll need more relief cuts per strip the further I get from the sheer line.

2) I can remove all strips, forms, etc. and throw them out in the yard where they're make a very hot and fairly satisfying fire. (Trust me, I almost exercised that option this afternoon after spending almost 5 hours tearing off strips & cleaning up cove edges by hand only to have it happen again) I would then need to start over with a different set of forms but maybe the new hull would be more cooperative.

Or, 3) I can remove all strips and start over without following the sheer the whole way up.

I think what's happening is this: Because the chine is very rounded on this hull, I started stripping at the sheer and bent the strips around the chine as I had when stripping the Raven (worked great on that hull). This is a much smaller boat, however, so the twisting & bending has to happen in a much tighter space.

I'm sure that strip width (a hair over an inch) isn't helping either but I think it's reasonable that I can minimize strip distortion by laying a starter strip parallel to the strongback (maybe just below the reference line I'd drawn to line up forms), lay another at the sheer and fill in between the two, tapering strips to fit as I'd done building my Freedom.

By doing this, I'll only be asking each strip to bend & twist in one direction instead of twisting in two directions at the same time. Shame to have wasted so much time and, honestly, part of me wants to go with option #2 above but, the only way I'll know for sure is to try option #3. Hopefully, I can correct the oil canning and someone will benefit from this info on a future build.

Demolition is scheduled for Sunday morning unless anyone has a stay of execution (and a better fix) in their pocket.

I hate to suggest this, but I suspect if you try cutting a few strips in half and try those, the problem will disappear. Those look awfully wide and when you are curving like that, I think the bottom and top of the strips travel a different line (the top and bottom travel length is different) and that is causing the oil canning. The closer the top and bottom is, the less the difference becomes ... so thinner strips likely won't have enough of a travel difference to show.

Just a thought.

Brian

Valid suggestion and one I hadn't thought of... we now have option #4.

I'm wondering which is easier: reworking strips to 1/2 inch widths (probably need enough of them to get past the stems, right?) or trying option #3.

Allan pointed out to me last build that mixing strip widths is a valid method and I agree with that, if you are already at the "buckle" point and can take that strip off and then proceed with the narrower strips, that just seems like less work. Especially if you are going to try narrower strips anyway.

Did that strip warp after you glued it into place ?
I've never had that happen on any of my Stemless hulls.
I start stripping in the middle of the canoe, and work towards the ends.
Where do you start stripping from ?


Jim

I usually start at one stem, cutting the short side & working my way around the hull (Bow overlaps on one side, stern overlaps on the other and then direction switches for the next strip up). It's worked really well in the past. After removing the 4 strips, I tried starting in the center and the distortion was, again, noticeable by the second strip so I'm satisfied that there was no difference and the root cause is somewhere in the strips themselves (width, material, grain) or in what I'm asking them to do.

When I did my Freedom, Bear Mtn had marked that the first strip be installed at the chine and the space between the sheer and the chine had to be filled in (or stripped past & shaved off) and I think that would be the best way to do this hull in the future. It seems that most people like an accent strip parallel to the waterline so (I think) they may solve the oil canning without knowing it simply by not following the sheer.

I think the Raven was far more forgiving because it's a larger hull (I like the accent strip following the gunwale and I knew that @memaquay had stripped his from the sheer [I believe @Roybrew might have also] which made it a no-brainer for me. In fact, I even rounded off the chine a little to make it easier).

In this case, the hull is not nearly as deep and the strips are now bending downward to follow the sheer, coming over the chine, twisting to lay flat on the bottom of the hull and then passing back over the chine to bend down to the other stem. It's just too much.

I think I'm going to use the pull saw to cut a straight line parallel to water line (similar to how we cut the center line but as far from the strongback as I can get before the strip distortion begins) and restart stripping from there. That will keep me from removing all of the strips and should reduce the twisting (If I'm right about the number of twists & turns being the problem).

If I still can't get it, I'll take off all the strips & start again making some thinner strips for bending over the chine (I'll probably need to make some more strips by that time any way... good thing I cut up way more than I needed in the first place)

This isn't exactly rocket science so I'll get it figured out. Thanks for all the suggestions.

I've had strips buckle between forms as you've just experienced. I too, got pretty bent out of shape about it...But, after a small delay of a day or two, those buckled strips (I had way more than you do) relaxed and conformed all on their own. There is a time constant associated with forced deformations. These off axis deflections introduce tremendous strain and it just takes time to allow intergranular slip.
Think about how easily steam bent wood conforms, it's really just reducing the time for the slip.

Anyway, the other issue as Brian mentioned upthread, is the strip width. Considering the strip as a simply supported beam, the stresses and resulting deformations are a function of all three axes...inverse square of the length, linear with the thickness, and cubed with the width. In other words, with other factors unchanged (thickness, length, material properties) the strength of the strip in that plane is a function of the width to the 3rd power. If the strip is 1/2 the width, it will be 1/8 as strong. In that case, the buckling will be diminished as well.

I've always built with WRC. Maybe it has to do with the wood you are using ?

If you have Faired your forms, the strips should lay flat.
It's not the hull design, as many have been built using these designs.
It's likely the wood you are using.
Too stiff to bend ?

Many Builders us a Herringbone pattern to eliminate the bending of the strips.
Here is a pic, from the Minnesota Canoe Assc. Builders Book.
It Illustrates the Herringbone pattern of stripping.
It's a form of splicing the strips, to eliminate the stress, on the strips in the middle.
I've seen many hulls built this way, and another benefit is the use of shorter strips.

Thanks Jim, That would certainly work and I'll look into that before I cut the waterline today.

The material isn't anything unusual this time. White Pine so probably the most common wood that I've tried.

Another benefit.
The herringbone method, makes it easier to keep the strips tight to the hull, giving you a true to the form shape.
Canoe designers, use this method for that reason.

Good luck with that Gamma, I've luckily never had that happen. I have had good luck using a heat gun to twist strips into shape near the ends before I glue and staple them down. It takes some of the pressure off the staples. I just use a couple of those irwin grip clamps to get leverage. It might be something to try.

Mark

Mixed results on tapering the herringbone strips.

I started at the stems & allowed the strip to run off the side when flexed as much as possible without starting to distort. I marked a pencil line on the back of the strip and tapered it a little long figuring that it would become more flexible as it became thinner.



It worked well to eliminate the distortion and I initially had to taper one from the bow, one from the stern and then a filler tapered both directions for the center.



After doing this twice, I was at the point where the two end pieces would overlap in the middle but by the 3rd, I was starting to get some distortion again and had to make a relief cut on the strip (these work pretty well BTW)



The upside to cutting the bead off is that the cove remains intact on the strip. When I was finishing the taper on the strips, I tried to round the edges a little to replicate the bead and I'm satisfied that I've got good adhesion.

BTW: The tip of the chainsaw file works great to remove the excess glue from the coves and a little bit of clean release tape works well to hold the thinned ends of the strips without damage



Bad news is that I'm losing ground in the middle of the hull. I'm now getting a full inch of coverage at the stems but, with the overlapping tapers, the last strip(s) only achieved about 1/4 inch in the midship area. I think I'll continue in this manner until I get the stems covered and then come up with a pattern of some sort for the bottom. I'll have to taper & fit strips to transition between the existing hull and the new strip orientation but I should be able to come up with something that looks like it was meant to be that way.

Tapering all these strips is a lot more work than tapering the few that were required to close the area between sheer & chine on the Freedom. I'm really wishing I'd stripped this hull that way instead of the way that I did.

As it stands, however, I'm too far along to bail out now so I'll keep picking at it until I get it closed up. (won't be able to see strip orientation on the outside any way when I'm done)

You have corrected the wave !
I know the Herringbone is more work and a challenge.
It looks like you have it !

Great pics by the way !


Jim

By the time I'd reached the top of the stem forms, the tapers were providing no coverage at all in the center of the hull so I moved to the center and started tapering toward the stems





After 3 or 4 of these, the strips were starting to run pretty straight down the hull and I was finally able to add another Cherry strip as an accent (I like to have some in there but thought straight Pine would hide all of the tapers more easily). I'll actually double the Cherry strip and close the football with White Pine on this one (you'll be able to see the wood inside)



I'm still not sure what all the buckling was about but, at this point, the strips are laying down nicely and I seem to be back to closing the football like normal. The tapers give a weird optical effect that I hope does not look odd on the inside (looks like there are bulges on the outside). I guess we'll see...

I did encounter some slight deviation as I closed in the football but only minor such as I've had on other hulls and I know that I can correct that before I glass by adding supports between the strongback & the low spot.

I got the football closed this weekend & started pulling staples. Hopefully I'll be able to get it sanded in the evenings this week and it'll get interesting this weekend.