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Re: Other: About Those Scarf Joints (or How I Brok
By:Bill Hamm
Date: 7/3/2011, 12:19 am

: So as I sit here in front of my computer, sipping on my whiskey, I
: ponder the day's events. I made a mistake. In analyzing it
: objectively, I've gained experience and learned a lesson or two.
: Maybe someone reading this will learn, too. Even so, I've also
: proven (to myself, if no one else) how strong scarf joints
: really are.

: My wife went out biking with two of her friends tonight. I try to
: paddle whenever she's running/biking, since she always travels
: along the Hudson Mohawk Bike Trail. There's numerous put-ins
: along its length, so those no reason not to. It makes the wife
: happy, since I drive her to the path, and I get an hour or two
: in of nice relaxing paddling. One of her friends has a husband
: who recently received a 10' plastic kayak, but hadn't actually
: put 'er in the water yet. It only made sense for him to hit the
: water, too.

: It was a nice hour long paddle, three miles or so total. Had a few
: power boaters buzz past with little regard to their wakes, but
: they kept a decent distance. I can't complain about the wakes,
: as they're a nice break from the flat water of the Mohawk River.
: A few fish poked about around us, munching on the afternoon's
: insects as they hit the water. Overall, it was a great paddle.
: We wandered back to the launch, a few minutes late but both
: convinced we could talk our way of trouble with our wives
: (honestly, honey, those power boaters were giving off huge
: wakes. We had to slow down and make sure we were being safe. And
: did I mention the fish!)

: Everything was nice until we got our kayaks back on the roofs of
: our cars. My wife has an '07 Subaru Tribeca with factory roof
: racks. They're spaced all of 30" apart, which makes it a
: bit of a balancing act once the 'yak is up on the roof proper.
: Up until today, I had also been (gingerly) using ratchet straps
: to tie the boat down. Obviously, that's not recommended, so I
: replaced them with 12' clamping straps from NRS. That was long
: enough for all but the front strap. I used a ratchet strap to
: carry the kayak to the launch, but I was convinced that I should
: not use the ratchet.

: Doing so required that I move the bow of the kayak forward on the
: SUV. That shifts the CoG beyond the frontmost roof bar, causing
: the kayak to tip forwards until it hit the hood. Still, the
: stern isn't but a couple of feet of the rear of the vehicle, and
: the bow doesn't protrude past the front. I thought I'd be fine.

: I strapped down the rear roof bar, then heard the pop. My gut did
: flip flops, since I first envisioned a broken roof rack on my
: wife's SUV. She'll kill me. She'll kill me dead. She'll kill me,
: and when I come back to haunt her, she'll kill me again, just to
: prove the point. I gingerly examined the rack, noting its intact
: state, and then shrugged with a general feeling of doom settling
: in the pit of my stomach. I felt that it wasn't good, but until
: I could prove otherwise, my rational mind was going to tell all
: my other bits to shut up and stop trying to riot. So I proceeded
: with strapping down the rest of the kayak.

: When I got done, I noted that the bottom of the boat around that
: front roof bar wasn't looking right. (I've been carrying the
: 'yak right side up, since it sits better that way than teeter
: tottering on the coaming). The skin was wrinkled, and the
: keelson seemed to bend much more than it should've. I simply
: made sure the straps were tight as I clambered into the car,
: while my gut was telling my mind "I told you so. Don't
: listen to me. See what happens. Maybe next time you'll pay
: attention. Blah blah blah." It's like my wife has taken up
: permanent residence in the general vicinity of my stomach.

: I picked my wife up, shook my head at the state of the keelson, and
: pointed it out to the wife. Oddly enough, she quieted down about
: my being twenty minutes late to pick her up. That's not a good
: sign, either. She knows that the keelson's not supposed to bend
: like that, and she's keeping quiet about nagging me because she
: expects I'm gonna be bawling over a broken boat. I'd almost
: prefer her nagging me (almost, mind you. Don't go tellin' her
: anything different. God knows what she'd do *grin*).

: Once I got back to the house, I could pull the 'yak off the roof of
: her Tribeca and take a good look at it. Now, I know I placed all
: the scarf joints right around the coaming. Most were within the
: coaming. Out of sheer coincidence I suppose, that front roof bar
: was placed right in the middle of the coaming when I tightened
: her down. That scarf joint on the keelson was right over the
: bar. All the weight of the front of the kayak was on that point,
: while I cinched the rear of the kayak down. The 'yak wasn't
: loaded up heavy, but all of it's 40 pounds (plus a few extra for
: the paddles, water bottle, sponge, and roll of duct tape) were
: placed on that point. I was certain that "pop" I heard
: earlier was going to be the scarf joint.

: After getting the boat onto the lawn, I could flex the keelson and
: take a good look at the damage. The scarf joint was fine for
: most of its length. One inch from the end of the joint, the wood
: had split vertically. It's a hairline fracture, and hard to see
: until you flex the keelson. I imagine the design the boat keeps
: the two pieces pressed together, the fibers naturally lining up
: and giving the appearance of a solid piece of wood until it
: flexes and the crack appears. The wood "above" the
: scarf joint at that point was thin enough, and hadn't made good
: contact with the other side of the joint, so I'm not surprised
: it gave way. On the other hand, that 12:1 slope makes for thin
: wood one inch away from the end of the joint, so even if it had
: held, I would have expected it to break instead of flexing with
: the damage. I'm sold on scarf joints, as long as they're cut and
: glued properly.

: I expect that if the boat was in the water, since the load is
: distributed across the rest of the stringers and the skin, there
: wouldn't be much deformation of the keelson. Even if there was,
: it'd be upwards until it impacted the seat or my buttocks (ok,
: maybe this isn't a minor issue). Still, I broke it, so I gotta
: fix it. I had some scrap wood left over from building her... a
: 16' long section of 1/2" by 3/4", made when I trimmed
: the stock down for the keelson. I cut two 12" lengths off
: and sanded the edges. The finished side I covered in a thin
: layer of Gorilla Glue (I don't have any epoxy, and the bottom of
: the boat is still wet from the paddle drips... I need that spray
: skirt, too). Slap the finished side against the keelson, roughly
: centered on the hairline fracture. It's awkward to clamp,
: though, due to the placement of the seat boards. The skin can be
: pushed away from the keelson, so I just lashed both ends of the
: repair blocks. I reckon that'll keep enough pressure on the
: Gorilla Glue to give it a decent bite.

: Come next winter, I suppose I could cut out the damaged section and
: try to scarf another piece in. On the other hand, I may just
: leave it as is. Every time I look into the cockpit, I'll see
: that rigged repair sitting between the seat boards. It might
: serve as a lesson and a reminder. Besides, it gives 'er
: character (like she needs more).

Hi Noel,

Good chance to try butt blocks, one on either side of the scarf, epoxied to the keel, will fix that problem.

I'm not talking about those straps, for now :)

Btw, when you load the boat on the roof, put the cockpit above the racks, they always overhang the ends of the car.

Bill H.

Messages In This Thread

Other: About Those Scarf Joints (or How I Broke My Keel)
Noel Bennett -- 7/3/2011, 12:12 am
Re: Other: About Those Scarf Joints (or How I Brok
Bill Hamm -- 7/3/2011, 12:19 am
Re: Other: About Those Scarf Joints (or How I Brok
Noel Bennett -- 7/3/2011, 12:27 am
Re: Other: About Those Scarf Joints (or How I Brok
Bill Hamm -- 7/4/2011, 12:19 am
Re: Other: About Those Scarf Joints (or How I Brok
David Bynoe -- 7/4/2011, 1:33 pm
Re: Other: About Those Scarf Joints (or How I Brok
ancient kayaker -- 7/5/2011, 12:08 am
Re: Other: About Those Scarf Joints (or How I Brok
Paul G. Jacobson -- 7/7/2011, 4:05 pm