How thick is your hull

doris

doris

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All the tosh about Bavarias, layups and hull thickness in the other post made me dig out the cutouts from my speed and depth transponders. On a Dehler 39, built in 2006, the thickness is about 23mm. These are at the very aft end of the forward bunk so well forward of the keel.


What about other makes? Any accurate comments?
 
On my British Hunter channel 31 the only thicknesses I know are at the transom and the hull bottom, about two thirds way back from the rear of the keels to the transom. In both locations the skin thickness is only about 6 mm. It is interesting to compare this with Snooks' Sadler 32, if the thickness he measured is the same throughout the boat then one would expect the Sadler to have a much higher displacement than the Hunter, yet the two are very similar: 4320kg / 4263Kg.
 
The Sadler thicknesses are really surprising, Sadler was a designer who was regarded as knowing a bit about engineering and even the very early reputedly overdesigned efforts at grp by Nicholson etc were thinner than that, once you were away from the keel. Maybe it was laid up on a Friday and again on Monday, naw, they would have noticed the smell of styrene.
Sudden thought, there must be a thick area in the transition from solid to sandwich?
 
My boat is incredibly thick, last week she ran aground in an area she's been sailing for years. After all this time she should have known there wouldn't have been enough water there at that state of tide but did she alter her course - no she didn't, she ran aground at 5 knots - stupid boat, thick, thick, thick!

Cheers, Brian.
 
snooks said:
Along the spine where the depth and speed transducer is, my hull thickness is about 35mm

The hull in non structural areas is about 15mm

Both are solid laminate

Sadler 32
Click to expand...

Find that difficult to believe with solid laminate. Looking up the boat specs the boat is about 2500kg after taking off the ballast. My RM 880 which is 12-20mm plywood (much lighter than fibreglass) and probably a similar size and is 2000kg without ballast. Either your laminate is a composite or the transducers are located in untypical parts of the hull.
 
Wait for it, this has all the ingredients of a pi$$ing contest 99.9% of which will be based on inaccurate, irrelevant or imaginary dimensions. The only thing that is really thick here will be the thought processes and their resulting prejudices.:)

Of course I could be wrong....
 
Robin said:
Wait for it, this has all the ingredients of a pi$$ing contest 99.9% of which will be based on inaccurate, irrelevant or imaginary dimensions. The only thing that is really thick here will be the thought processes and their resulting prejudices.:)

Of course I could be wrong....
Click to expand...

i have original drgs but cant be arsed to look up the details :rolleyes:
 
JimC said:
On my British Hunter channel 31 the only thicknesses I know are at the transom and the hull bottom, about two thirds way back from the rear of the keels to the transom. In both locations the skin thickness is only about 6 mm. It is interesting to compare this with Snooks' Sadler 32, if the thickness he measured is the same throughout the boat then one would expect the Sadler to have a much higher displacement than the Hunter, yet the two are very similar: 4320kg / 4263Kg.
Click to expand...

Yes, but you can't really compare thickness in a meanngful way. Hunter engineered their boats very well. Essentially the laminate is pretty thin aft and much, much thicker by way of the keels and the fwd sections where the stresses are higher. I never measured the thickness when I cut the transducer holes but they took A LOT of cutting! Also, having seen mine being moulded in Essex, she had very little chopped mat in the hull and seemed to be made mainly of some reasonably exotic woven rovings and this, whilst stiffer and stronger will be lighter and thinner.

Whilst the Sadler was built some time ago I would still think the hull thickness would vary depending on the area
 
Moody 31 forward of the twin keels near the centre line, 20mm of solid GRP. Thats about twice the thickness of the flak jacket plates we used to wear in Belfast.

Pete
 
On my Moody33, thickness at about 12" above the waterline is about 8mm - I still have the piece of GRP in my shed. On the bottom when I renewed the toilet outlet skin fitting it was nearly an inch thick and on the transom a minimum of 12mm when I drilled a hole for a new exhaust outlet.
 
In order to get the definitive answer I've just been out and cut the boat in half to find out.
This is an end-grain balsa sandwich construction so I gues the resin at each side is about 2mm

Cuttingupboat_6.jpg
 
My hulls are 7mm of grp plus 5mm of foam. There are no stresses from chainplates or ballast keels. My previous boat, a 39 ft tri, had 2mm grp either side of 12mm foam.
 
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