Building a '93 Caravelle 1750 Classic Bowrider

[Reserector_]

Today I put the bunny suit and respirator back on and started cutting on the bottom of the cap to expose the rotted wood that needs to be replaced.
Weapon of choice was an angle grinder with a cut-off wheel. Quick and risky.

I thought I got all of it, but there is s good bit more buried in the back.
Oh well. I didn't come this far to cut corners now. It all has to come out somehow.

Question: have any of you seen plywood stiffening that looks like this? (7th and last pictures) It's like a bunch of rectangle pieces fitted together instead of a single sheet.
Maybe this area is not actually flat? Hmmm. I'll have to check out with a straight edge in the daylight.

 

[chevymaher]

I saw the guy on boatworks do one like that. If it is pieced in it probably isnt flat.

 

[kcassells]

Yea back in the day and still some today they placed squares down in random grain opposites. It actually creates more strength. Usually easy to get out with chisle and hammer or multi tool. Then grind. Like a parkay floor.
Balsa core was always installed in this manner.

 

[kcassells]

Heck you could just lose all that and do a flush floor with transom drains.

 

[kcassells]

Before and after.

 

[Reserector_]

Heck you could just lose all that and do a flush floor with transom drains.

???

 

[kcassells]

Then again maybe not. Just went back and looked at the transom config. Ahhhh Nope, nope, nope.

 

[Scott Danforth]

Question: have any of you seen plywood stiffening that looks like this? (7th and last pictures) It's like a bunch of rectangle pieces fitted together instead of a single sheet.
Maybe this area is not actually flat? Hmmm. I'll have to check out with a straight edge in the daylight.

end-grain balsa core....... extremely common boat core material (still used today) it is to core non-flat areas and areas that re non-critical.

 

[kcassells]

Like Scott says..Mine and others were ply squares.

 

[Reserector_]

It appeared to be plywood. It sluffed off in layers. I'll look closer when I get home tonight.
It looks like the blocks were aligned in rows. Almost like planks. I thought maybe that was how they used up scrap at the factory.
The horizontal surface is 3/4" while the vertical surface is 1/2"

 

[kcassells]

No they did it for strength actually. As I said earlier. Multiple pcs of wood with grains in opposite directions. Probably before all the new stuff out here today like marine ply.... stuff w/no voids or completely a composite.
Thats all.
Balsa would be a solid endgrain as mentioned by Scott but ply peels off in layers. Especially when wet.
At this point in your build really doesn't make a diff. other than gaining info. And that is good.
Also helps to be aware for the next purchase. Cause it never ends.

 

[Reserector_]

......next purchase. Cause it never ends.

Next purchase? No. I plan to have my will written to include using this boat to give me a Viking funeral. It dies with me! LOL

 

[Reserector_]

Balsa would also serve as flotation, correct? Not that it matters. I'm going with plywood. Just curious why they would go to that much effort.

 

[tpenfield]

Balsa would also serve as flotation, correct? Not that it matters. I'm going with plywood. Just curious why they would go to that much effort.

Usually you want the core material to be semi-rigid and lightweight. Balsa and foam both provide those properties. When the need is more along the lines of flotation, you tend to see foam used rather than balsa.

A purely backing material or rigidity need on a low to mid-range boat, you will usually see plywood, as was the case with your boat.

 

[kcassells]

Next purchase? No. I plan to have my will written to include using this boat to give me a Viking funeral. It dies with me! LOL

Yea I said the same thing on my first boat... And now on this boat.

 

[Reserector_]

May have had nothing to do with curve or flat. This part is definitely flat and was done the same way with 1/2" thick brown cheese in blocks.

In this shot, before the fiberglass was removed, you can see how it was reinforced with blocks. There was resin between some of them. The PO must have cut that godawful opening to access the back of the seat or something.

Sorry for the blurry photo. I have torn (and repaired) retinas and can't tell if the camera is focused or not in the daylight.

 

[Reserector_]

I looked at it this evening. Definitely plywood pieces. Not balsa or plank material.
It's not perfectly flat, but seems like it's supposed to be. It is the swim platform, after all. There is some distortion from it being stuffed in the hull upside down and neglected for ten years. I had to pull it into shape with a clamp during the test fit, and that is what I saw when I laid a straight edge on it.

 

[Scott Danforth]

Balsa would also serve as flotation, correct? Not that it matters. I'm going with plywood. Just curious why they would go to that much effort.

balsa core is about 1/3 the cost of ply....... simple economics.... throw the boat together as cheaply as possible to get it out the door (in under 20 hours from mold to trailer). its all about making money.

 

[Reserector_]

Here's a theory. Maybe they used cut-up plywood where a sheet would be a real problem if it were warped. Think about it; they add the reinforcements while the shell is still in the mold. That's no place to deal with a bowed piece of plywood.
In that situation, using multiple pieces as a core will allow the shell to hold its shape regardless of curved or flat.

 

[Scott Danforth]

Nope, boat builders dont use any of the scraps to make anything. too much labor

they get Balsa core, and for production boats, it comes pre-cut to size. economy of scale makes a difference.

the image below shows how flexible balsa core is.