Project TW28

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colinhart
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Re: Project TW28

Post by colinhart »

Earlier posts had some discussion re ballast, how much did you guy put in the boat and what did it consist of. Off to the Southampton boat show soon looking at an anchor windlass thinking of a Lofrans as a friend is an agent for them any thoughts on these. Also a plotter for coastal work and a good fishfinder for filling the freezer any experiences please. its great to be back.

fallguy1000
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Re: Project TW28

Post by fallguy1000 »

Furuno is world class, repairable, long running..

I bought a Raymarine Axiom for the realvision product, but the Furuno is the one I am using, Furuno has real customer service as well. Yup, a person you talk with..
My boat build is here -------->

viewtopic.php?f=12&t=62495

fallguy1000
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Re: Project TW28

Post by fallguy1000 »

Those in sole hatches...how you plan to seal or gutters?
My boat build is here -------->

viewtopic.php?f=12&t=62495

colinhart
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Re: Project TW28

Post by colinhart »

I will post a picture re the hatches

fallguy1000
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Re: Project TW28

Post by fallguy1000 »

colinhart wrote: Sun Sep 10, 2023 4:07 pm I will post a picture re the hatches
I had to change my drains, so just trying to help.
My boat build is here -------->

viewtopic.php?f=12&t=62495

colinhart
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Re: Project TW28

Post by colinhart »

Image

colinhart
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Re: Project TW28

Post by colinhart »

Sealed hatches into the deck with sika flex the non slip matting in by Treadmaster. Its really good stuff as the adhesive is already applied and you just have to peel off the backing paper. I have built in 3 drains into the cockpit so hopefully that will be suffice to shed water ingress.

Jeff
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Re: Project TW28

Post by Jeff »

Nice progress!!! Jeff

fallguy1000
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Re: Project TW28

Post by fallguy1000 »

I love the boat and work done so far. The amount of freeing ports appears insufficient for broaching seas.

The formula for freeing ports varies, but a general formula for that boat is A = 0.7 + 0.035L, where L is the length of the bulwark in meters. This is for a commercial fishing vessel bringing lotsa water onboard, so it would be obscenely higher than needed.

So, let's say the port bulwark is 2 meters; probably a bit less, but close.

A = 0.77 m^2

It can be reduced for each increment of height below 0.9M. So, let's say your bulwarks are 0.5M. Then you can reduce it by this much

A reduction = (0.9-0.5)/0.1 = 4

4 • 0.04 = 0.16 reduction

So, the commercial calculation is 0.61 m2..

Imagine a hole that big on the side of the boat! It would be nuts, right?

So, I got some other help because my cockpit is massive. And we decided the freeing ports for the cockpit area I have would be decent at 15" wide by 6" high times two.

My cockpit area is 16'x7' with similar bulwark height to yours. So, my freeing port calc is

A = 1.25' • 1' or 1.25 square feet for 112 square feet of cockpit. Later, I reduced the heights of the freeing ports a bit and am closer to 1.12 square feet for 112 square feet. Or 1% of the cockpit area is the area of the freeing ports. I can open the cockpit doors if we are in a broaching condition and get a lot more, but not unless prepared

So, returning to your space. If the cockpit is 6'x6' or 36 square feet; you want about .36 square feet in freeing ports. Maybe you have enough?

So much depends upon where you intend to sail the boat as well, but the 1% of cockpit area is decent guidance. Those freeing ports of yours are fine for rain, but a but small for broaching seas. Keep that in mind if you plan to come into port by a surf each time..

My best..boat looks great.
My boat build is here -------->

viewtopic.php?f=12&t=62495

fallguy1000
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Re: Project TW28

Post by fallguy1000 »

A 4"x4" scupper is .3' • .3' or 0.09', so maybe my intuition was wrong and you are good..
My boat build is here -------->

viewtopic.php?f=12&t=62495

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