Foam core thickness and density

[Willallison]

Here's a "how long's a piece of string" question for you...
Can anyone give me an estimate of thickness and weight (kg/sq.m) for foam core panel required in the construction of a 30-odd foot powerboat.
I have 2 boats in mind - Option 1, some details of which can be seen in its own thread on this web site.
The other is about 11m LWL, 3.7m beam, displacement 5000kg, top speed 30+ knots, inboard power.
I only require the info for rough weight estimates at this stage.
Even better - an on-line source of where I might be able to work this stuff out......

[BrettM]

Try
Bottom 11.8kg/sqm 22mm (~15mm core 80kg/cu.m)
topsides/deck 9.3kg/sqm 18mm (~12mm core 80kg/cu.m)

This is some generic data I had for a 30'x10'4" beam 4000kg boat

Obviously, it depends on how long your string is... and what is has to do...

brett

[Willallison]

Thanks Brett.
I assume the numbers you've given are for normal glass encapsulated foam - nothing too fancy.
They'll give me a good start, thanks again

[BrettM]

pretty much and E-glass foam laminate. Nothing too fancy.
Brett

[Polarity]

Hi Will
I asssume you saw this...
http://boatdesign.net/articles/foam-core/index.htm

[Willallison]

Yes thanks - I did see that. There is a fair bit of general info around on this type of construction, I was after more specific examples of just how thick and heavy the laminates should be for a particular sized boat.

[Jeff]

You might also want to email Trevor Gundberg directly - Trevor.Gundberg@diabgroup.com - and see what example and quick calculations he can supply you with. I've found Trevor to be a great person to deal with.

Maybe we will also get him to put together a follow-up article for us this fall with more specific examples of prelim calculations and a few more detailed cross reference charts.

[Willallison]

That sounds fantastic Jeff.
I'm always a little hesitant about approaching people directly about this sort of stuff - my knowledge of the subject is limited (to say the least!) and I hate appearing to be a complete goose - probably as much as they dislike being pestered by them!
But I'll drop him a note - and just say you sent me!!

[Willallison]

Jeff,
I contacted Trevor as you suggested. He was straight back to me and very helpful - thanks for the tip

[Evolution Yacht]

Sorry I am so late to this thread, but Dave Gerr's book boat strength has a lot of info on how to calculate prelim scantlings and weight calcs.
SG

[JEM]

I've heard from 2 designers the Dave Gerr's book has some short comings. What are they? Is it true? I don't have enough knowledge to express an opinion about it.

[sorenfdk]

I think Dave Gerr's book is quite good, but not if you're into building very light.

[mistral]

Originally Posted by sorenfdk

I think Dave Gerr's book is quite good, but not if you're into building very light.

come on Soren ,don't be shy , give us some good suggestions about related books on this topic, we'll greatly appreciate them

mistral

[sorenfdk]

If I knew about any books about building lightweight boats, I would be happy to tell you about them, but unfortunately I don't...

If anybody does, please don't hesitate to tell us about them!

[TheFisher]

Personally, I'd accept a modest weight penalty for the benefits of additional strength.

The sea is an unforgiving mistress