Inner stem damage

Not personally, but a student whose HSC woodwork project build I was supervising had something similar.

While he was sanding, the kayak fell off the stands and the foot of the stand punched a hole the size of your fist through the hull.

The repair was very nearly undetectable of the outside and wasn't obvious on the inside.

Been there.  My first and only kayak drop about 8” onto the cross bar on the support stand after I flipped it over to start stripping the deck.   It cracked on the keel centerline about half the length of the kayak.  I was so disheartened I didn’t touch it for a full year.  The repair took about 30 minutes.   That was the first mistake of many.  I didn’t let the others frustrate me that much. 
 

Aaron

...I have had other frustrations. I have not built a stripper yet but I have built 6 S&G kayaks. I remember one project where I stitched the entire length of a kayak only to discover that it wasn't perfectly straight, so I had to untie all of the wires, cut new ones, then retie the panels and watch more cafefully while the panels were joined to ensure that the lines were better. That was 18 years ago. More recently, like three weeks ago, I mixed a batch of epoxy and coated the hull of my expedition kayak only to discover the next day that it didn't set. Seems I mixed a 9:1 ratio instead of a 3:1 ratio. I really really wanted to enjoy my anger and self-frustration for a month or so, just stew about it and walk away from the project but it needed to be completed or I wouldn't be doing much kayaking/photography this summer. The bad epoxy removal took 20 minutes and I was back in business. Even after so many years, I still make simple mistakes. Thing is, all mistakes are simple to recover from if we keep our perspective...why are we doing this amyway...makes it easier to get back to business.

Robert N Pruden

I'll add to the list!  I'm on my 3rd strong back.  I just cant build a plywood box that is straight enough.  I'm leaning towards spending the $150 on an aluminum strong back in order to remove a few more variables.  The recent madness has forced me to adopt more patience, however, and a focus on doing the job correctly rather than completing it.  Process vs outcome...

I just cant build a plywood box that is straight enough.

Even with the 'internal strongback'  method (which I don't use) the strongback doesn't have to be perfectly straight if you can fine-adjust the mold positions. Make the openings in the molds a bit bigger and shim?

As long as the molds are aligned, (not necessarily level either) the strongback just needs to be stable, not perfectly straight.

John,

Thank you for your reply.  I'm going to give my last version a shot and see if I can shim the forms as you suggest.  I was so diligent in cutting/routing the 2x4 holes in the forms that I am hesitant to go back and re-cut (I'd like to avoid tolerance stack!).  Seeing as I am in aerospace manufacturing, it's pretty easy (and affordable) for me to source the aluminum.

My internal strongbacks are 3/4" plywood rabbeted on the edges. They are close to straight but not perfect. I cut the form center holes approx. 1/4" to large then I snap a chalkline down the top of the strongback and chalklines on each side to align forms. Makes a very easy alignment, zero shimming and no problems to date.

John, I have been thinking about your suggestion to open the strong back holes to increase room for fine adjustments.  Let me ask this - is the pressure from the spacers, once they are tightened, enough to keep the forms in place, even if some of them are not resting on the strong back?

I think we were typing at the same time.  I made mine out of 3/4 in plywood also, but used some older pieces from around the shop.  There is a slight curve in mine (about 3/8) and one end is about 3/8 higher than the other.  Also, a slight twist, which can be overcome with shims.

 I was so diligent in cutting/routing the 2x4 holes in the forms that I am hesitant to go back and re-cut 

You could probably enlarge the holes in the forms in a fairly precise way with a router/rabbeting bit and a pattern bit from the other side.

But, if you can get the aluminum easily, that might be quicker. (Assuming that's a material you will be happy working with.....)

If you use wood wedges to shim the forms in place, I think they should 'stay put' fairly well, but you need to ask somebody who uses that strongback type.

I think I've pulled the discussion here a bit off-topic? Now we are listing all the reasons why I don't use 'internal' strongbacks!

My apologies!

:)

After positioning the forms in their approximate location on the strongback I screw 1x strips to the strong back both vertical and horizontal. That way, while positioning the forms, I do not have to consider keeping them vertical/horizontal, it is built-in. Then temporarily shim the forms into final position. Once I have the forms in the correct position I install one screw though the 1x strips into the forms both vertical and horizontal. Do one last "alignment check, then insert a second screw in the 1x both vertical and horizontal. Makes a very solid structure to work on.

As I mentioned before, I have always used full size prints spray glued to the forms to cut them out. (bandsaw close to the line then finish up on a disc sander) These patterns always have 'alignment marks' drawn on them. I spring clamp small wood strips to each mark so during final alignment on the strongback I can visually sight down these sticks. There have been times where, even though the sticks were in alignment, the actual boat form looked better with some of them somewhat out of alignment.

Which only means I probably built it out of alignment but, it looked good to me :)

One tip - keep a wet rag handy when gluing strips and gently wipe off the excess glue both inside and outside each strip as you go. Makes scraping/sanding much easier later. And also, in my limited experience, cutting strips with a 3 degree bevel then hand planing to final fit is way much easier than the routing bead and cove route.

One last thing on the 'learning curve'. I have a tendency to put-off doing things I don't know how to do. I always have to do them sooner or later and almost always I have come to the same conclusion, "hey, this isn't as hard as I thought it would be"  Enjoy your journey :)

Back to the topic of mistakes and accidents-

The one that nobody talks about is 'building the wrong boat'.  Either picking an inappropriate design or just a design that doesn't perform as expected is pretty common. It's a tough realization after spending many hours on the build, even if the main pleasure is in the building.

What builder is going to admit:'It's beautiful, but it doesn't perform on the water as well as my friend's glass factory boat." ??

It can happen.

"Not enough room for my feet" is another problem - I do more testing now!

yes, its very easy to do.  

the set of pictures below show how.  basically, you just shave down the bow with a block plane to the new line where you want to infill the outer stem, lay in the new material, and shape it.   

i usually shave down the bow to take it back to a point where i have between a 1/2 inch to 3/4 inch of width which corresponds to just exposing the inner stem.  and than build back from that point.  hope that helps.