fiberglass hull thickness

[fallguy]

It is not an existing boat but it is a beginning of a project ......... to have a basic starting point, then I will develop the project with more precise calculations. Thank you all for your technical support.

The hull is not really backed into quite as such.

The service demands dictate the hulls. Horsepower, speeds planned, other such stuff.

A recreational 8 meter boat probably doesn't require 8-10 layers of biaxial fabric. That would be sort of a lot, based on my very limited knowledge of these things. My hull bottom has doubled triax inside and out for a 10meter cat b vessel. The triax is about 22-24 oz depending upon the brand, so we have about 44-48 oz per side. Let's say you use a 17 oz biax; 3 layers a side would be close-ish, sort of.. A thicker core material with a bit less glass is more practical unless your hull has some unusual ..service requirement.

I don't profess to be an expert, just see some flaws in the approach. More glass is more expense and more weight as well... my 2 cents..

 

[Gianf1041]

I evaluated approximately for a hull of about 8 - 8.50, sandwiches with thicknesses estimated from 20mm to 12 - 9 mm ......... for deck and deckhouse 15 -18 mm calculated with their surfaces. However they are rough estimates.

 

[fallguy]

I evaluated approximately for a hull of about 8 - 8.50, sandwiches with thicknesses estimated from 20mm to 12 - 9 mm ......... for deck and deckhouse 15 -18 mm calculated with their surfaces. However they are rough estimates.

What type of hull, hp?, speeds?

 

[Gianf1041]

as I said, it's all to think about ........ multi-chine hull ....... speed ??? ..... 7-8 knots max ......... ?? ...... HSPD 25-30 hp, SA / D ratio ....... min 8 ...... maybe a small motorsailer.

 

[fallguy]

You probably won't need much on the motoring side of things. Sailing altogether different.

 

[Mr Efficiency]

One wonders what the point of the original question was.

 

[Gianf1041]

I am making comparisons with other boats similar to my idea of a small motorsailer ........... Fischer 25, Dartsailer 27, Orion 27, Bristol 27, Albin Vega 27, LM 27, ...... .just to have some general indications.

 

[BlueBell]

Gianf1041,

Good for you to look ahead, to plan ahead, to dream.

Perhaps it is an English issue, I don't know.
It's taken me awhile to figure out the answer
to your original

How much could an 8 mt fiberglass hull with an average thickness of 20 mm weigh?

It could weigh way too much. Way, way, way too much.
But, you didn't mean solid polyester.

So, what's the rest of the dream?

 

[waikikin]

I am making comparisons with other boats similar to my idea of a small motorsailer ........... Fischer 25, Dartsailer 27, Orion 27, Bristol 27, Albin Vega 27, LM 27, ...... .just to have some general indications.

We must have some pictures then..

Jeff

 

[Gianf1041]

Ok, I apologize for my english, I am not very familiar and I have to help myself with the google translator, however I try to translate my questions and your answers correctly, fortunately we are all talking about topics we know and this I think helps us a lot .

 

[BlueBell]

No need to apologize, my Italian is terrible, well, non-existent really.
I only speak one language, you speak at least two!

One of the most important things with boats is that you get one,
or build one, that does what you want it to.
So, what do you want to do with your boat?
Fishing, speeding, going slow, loading everyone on board and going cruising for the day.
What?

Then, List what priority do these fall in to? Most important to least important.
Then, make sure the boat will do these things and do them well.
Make sense?

 

[Gianf1041]

I say this: mainly coastal navigation to the Mediterranean sea, a little bit of a little over there .......... so the boat will have to be tailored for a retired man with a wife and a dog ... ........ what could be better than a good motorsailer?

 

[Gianf1041]

In the 70s and 80s I raced on catamarans, now I try to draw some boats.

 

[Gianf1041]

How many layers of fiberglass fabric are needed for hull lamination with a thickness of 15 mm

there are thickness tables of practical use that indicate approximately the number of leathers needed ....... ??

 

[ondarvr]

The number of layers to achieve 15mm depends on too many variables. You need to know which glass fabrics you plan to use, plus the method. Hand lamination will require far fewer layers to reach 15mm than infusion no matter what fabric is chosen.