HB16

Power Boats only. Please include the boat type in your question.
jacquesmm
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Re: HB16

Post by jacquesmm »

Don't use less than 12 mm for the bottom please.

Edited: I wrote sole for bottom at first. See below.
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bklake
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Re: HB16

Post by bklake »

Same for the bottom?

I figured the span between stringers was too much for 10mm on the sole. But, I had to ask.

fallguy1000
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Re: HB16

Post by fallguy1000 »

The main issue with dropping ply sizes is the support from 10mm ply when not on water is sketchy. A large man standing in a panel center can crack it. Almost for certain 6mm WILL crack. 10mm probably won't, but offers nearly no safety margins. 10mm is really 9mm, btw

The hull can also crack if you go up on a stone and point load woth weight above.

In boat building, margins of safety are typically on the orders of 3 so people don't die.

Do NOT skimp on the hull thicknesses.

Also, the HB16 is a displacement craft, the only reason to make it lighter is to allow more loading. A 16' displacement boat make 30-50 pounds lighter will have nearly no effect on speed. All you gain is the ability for more load, ftmp.
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jacquesmm
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Re: HB16

Post by jacquesmm »

I wrote sole but it should have been bottom, sorry. No shortcuts there.
12 mm for the bottom.
Same for the sole.
Stay with specifications please, there is very little to save in weight or cost.
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bklake
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Re: HB16

Post by bklake »

I'm pushing the weight limit of my floating dock. 100 pounds saved could be the difference.

I will stick to the plans. Just wanted to ask.

fallguy1000
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Re: HB16

Post by fallguy1000 »

bklake wrote: Wed Jan 20, 2021 2:13 pm I'm pushing the weight limit of my floating dock. 100 pounds saved could be the difference.

I will stick to the plans. Just wanted to ask.
If you want to save weight; you could build internal non structurals from marine foam. Using vacuum would lower the weights more.

For comparison.

1/4" okume 4x8 18# or 0.5625# per sqft
Add 6 oz glass and epoxy each side is 24 oz/yd or 0.1667 per sqft
Total is 0.7292

12mm corecell with 12 oz glass each side vac bagged to 65% resin is 0.4837 per sqft, no vac 0.542

Benches, console, other items 50 sqft is a savings of 12.25 pounds. Lots of extra work for that 12#, but a way to achieve it.
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viewtopic.php?f=12&t=62495

bklake
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Re: HB16

Post by bklake »

fallguy1000 wrote: Wed Jan 20, 2021 3:25 pm
bklake wrote: Wed Jan 20, 2021 2:13 pm I'm pushing the weight limit of my floating dock. 100 pounds saved could be the difference.

I will stick to the plans. Just wanted to ask.
If you want to save weight; you could build internal non structurals from marine foam. Using vacuum would lower the weights more.

For comparison.

1/4" okume 4x8 18# or 0.5625# per sqft
Add 6 oz glass and epoxy each side is 24 oz/yd or 0.1667 per sqft
Total is 0.7292

12mm corecell with 12 oz glass each side vac bagged to 65% resin is 0.4837 per sqft, no vac 0.542

Benches, console, other items 50 sqft is a savings of 12.25 pounds. Lots of extra work for that 12#, but a way to achieve it.
Just like road bikes and airplanes. That last few pounds/ounces costs the most. Getting into vacuum bagging could get real expensive. Unless I build multiple boats. Hmmm.

bklake
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Re: HB16

Post by bklake »

jacquesmm

Can I get a ruling on the seams in the stringers? Nesting shows 6 identical pieces to make 3 stringers. Should I shift the nesting so there is an overlap? The stringer tutorial suggests that the seams should overlap and not be in the same place.

Thanks

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Re: HB16

Post by jacquesmm »

Yes, the seams should be offset. The nesting should show that but the purpose of the drawing was just to show the amount of plywood needed, not to show the exact location of each stringer on the panels.
Just slide them back or forth and it will work.
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bklake
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Re: HB16

Post by bklake »

Still planning and figuring.

Could the NidaPlast panels be used for the sole? What thickness? Not an inexpensive option but looks like roughly 100lbs saved. I'm planning on taking out the step down for the cabin. It will be a flat floor from the transom to the step up on the forward deck.

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