DE 27.5

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dennisb
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DE 27.5

Post by dennisb »

Looking for help.

I am getting ready to purchase fiberglass cloth and tap. From the material list for the boat, I need 480 yds of 45/45 12oz 6" wide tape. I can see on the plans where this tape is used.
The material list also calls for 9oz 4" wide woven tape, 50 yds, I don't see on the plans where this is used.
Can someone point me to where it is used.

Thanks

fallguy1000
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Re: DE 27.5

Post by fallguy1000 »

I can only answer typically.

Typically, light woven tapes are not structural and would be used for light holding needs.

For example, on my boat, light tapes are used on lids or doorways.

For a boat as large as the one you plan to build, some light tape seems practical.

I do not know if puzzle joints or butt or scarf joints are taped with 12oz biax or light wovens, but wovens may make sense because they would not alter the thickness much for a temporary hold until skins are applied.

No epoxy puttied joint can go untaped because they will open.
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dennisb
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Re: DE 27.5

Post by dennisb »

I believe this question is for Jacques.

I have a question on the number of layers of tape to use on the putty joints. I am building a 10% stretched DE 25. In a pervious post, Jacques recommendation is to double the layers of fiberglass on the hull, inside and outside. So I will have 4 on the bottom inside and outside, and two on the outside sides. Should I double up on the layers of 6" tape covering the putty fillets ?

Thanks for your input.

Dennis

TomW1
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Re: DE 27.5

Post by TomW1 »

Not needed a single splice will hold the two boards together, while the extra fiberglass will strengthen the hull further strengthening the joints.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

dennisb
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Re: DE 27.5

Post by dennisb »

Thanks for the feedback

fallguy1000
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Re: DE 27.5

Post by fallguy1000 »

dennisb wrote: Sun Apr 17, 2022 1:36 pm I believe this question is for Jacques.

I have a question on the number of layers of tape to use on the putty joints. I am building a 10% stretched DE 25. In a pervious post, Jacques recommendation is to double the layers of fiberglass on the hull, inside and outside. So I will have 4 on the bottom inside and outside, and two on the outside sides. Should I double up on the layers of 6" tape covering the putty fillets ?

Thanks for your input.

Dennis
Tapes would not change. So, 2x Tom

I understand you want Jacques to answer. Sometimes answers are elementary. I do my best to disqualify when I am unsure.

I am concerned with something else here.

Can you tell me what the glass schedule is for the DE25?

I think doubling sounds excessive and probably Jacques ought to be given a chance for another look. I seem to recall an off the cuff conversation..

For example, if the glass schedule was db1200 each side, doubling it would be a lot. That is almost enough glass for 5/8 foam core.

If it were 6 oz, doubling would be okay, but twice the work of a 10 oz.

I just think you ought to re-verify with Jacques.

I have a pretty decent intuition on laminates after 4.5 years of messing with everything from veil to triax.

A 10% increase to the vessel is probably within margins and doubling all the glass sounds unusual to me...unless it were a light woven. Even a 10 oz woven doubled would be a strange way to go versus say db1700 or db1200.

And double glass really drives costs for glass and epoxy and time/labor.

All the best. Dan
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fallguy1000
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Re: DE 27.5

Post by fallguy1000 »

I did go back and review and JM only said to add a layer of glass to the bottom.

If you have not ordered glass, I really think you ought to ask again on the glass schedule.

Since I don't know the glass schedule, I can't comment further, but doubling both sides could really be an awful lot. Moving from db1200 to db1700 is a really big move structurally, for example. Doubling 6 oz is not a big deal. Doubling 10 oz woven is sort of odd..etc..
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dennisb
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Re: DE 27.5

Post by dennisb »

Hi fallguy,

The original glass schedule per the plans is:
Inside bottom - two (2) layers of 45x45, 12oz
Outside bottom - two (2) layers of 45x45, 12 oz
Outside sides - one (1) layer of 45x45, 12 oz

I have not purchased any cloth yet, but will need it within 2 weeks.

fallguy1000
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Re: DE 27.5

Post by fallguy1000 »

No way does that boat need 48 oz of glass each side Dennis. That is a schedule for foam hulls, but bad at all 45/45!

I can't supercede the designer, but I strongly suggest you ask JM to review the glass schedule again.

I believe you asked a question and got an off the cuff answer, and then I believe you also misinterpreted because he never said to double the inside.

8 layers of 12 oz biax is literally 1/4" of glass! Not to mention all those layers would be running 45/45 and none 0/90 to pickup strength another way..

It would not make any sense to put that much glass on that hull and plywood, too. That is almost a layup for all glass and no ply!

So, please don't.

Give Jacques time to reply.

1200 db is like my favorite glass to use, but not 8 layers of it...
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fallguy1000
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Re: DE 27.5

Post by fallguy1000 »

I would tend to make some safe assumptions here that 3 layers of db1200 outside and 2 layers inside would be plenty. Again, not the designer, but this is 3 less than you are discussing. JM originally stated doubling the glass on the bottom, but you ought to ask him if he really wants 48 oz on the bottom...and you ought to get a uni in there if you ask me, Or a 10 oz woven. So, maybe jist adding the uni would be good for some 90 strands.

Make some assumptions, let's say the boat is 2 meters wide on the bottom. And 9 meters long. Call it yards at 18 per layer for simplicity.

Glass and epoxy per layer is 1.5# per yard.

Each layer is 27 pounds. 8 layers is 216 pounds of glass and epoxy on the bottom! 108 pounds of epoxy is like 12 gallons for just the bottom..

Anyhow, double check. Who are you buying glass from?
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