that was something about your hull for the new boat...3 ? kg/sqm. caused a fuss on crewnz. what core/laminate is that then, foam + 300g carbon db? what is carbon db cost? in fact what is 10mm foam too, cmopared to 5mm foam , less than double price as with most bulk gets cheaper.   talking about sharp bows on crewnz - how sharp is sharp? I mean when surfing down into the trough what's the differenc between monohull fat bows, catamaran bows and then harry bows at the most narrow end of the scale?   doug at houes in mandurah today --- On Thu, 11/6/09, Rob Denney <harryproa@gmail.com> wrote: From: Rob Denney <harryproa@gmail.com> Subject: Re: [harryproa] Re: preglassed panels....weights To: harryproa@yahoogroups.com.au Date: Thursday, 11 June, 2009, 4:58 PM Not sure what 3.5 kg panel you are referring to, but I calculate panel weight as follows: weight of glass = weight of resin so weight of glass *4 plus core thickness in metres * weight per cubic metre (80 is  near enough for both foam and polycore, cedar is 350, kiri 290) plus 200 gsm per side for foam and polycore, 50 gsm per side for timber. so 400 gsm glass either side of 10mm foam will be (4*0.4) + (0.01*.08)+( 2*.2) = 2.8 kgs per sq m. regards, Rob On Thu, Jun 11, 2009 at 2:47 PM, Doug Haines <doha720@yahoo. co.uk> wrote: as usual, I am not too sure what you're on about, but sounds possible.   I am using up odd bits of core to make shelves/tablette/ bunk so had to shape and work lots of bits. took all day long and very fiddly. a piece of foam you can make a pencil line and cut it with a knife and voila!   this is mostly 5mm and some 10mm, the bigger thick panels would have even bigger holes .. to fill!   On panel weights, I was starting to list the per sqm weights....   sidecar - elementarry, 5mm core and 260g db: 1.0 kg glass/resin + 400kg foam or 1.4 kg kiri core. plus wet out of foam I think was about 200g per sqm. Is there a wet out /soak in initial amount of resin to coat onto kiri?   anyway that's 2.0 kg persqm of foam / glass panel or     3.0 kg/sqm of kiri / glass.   not sure how much bog counts as, seems like it uses up heaps of resin, but most of that is sanded off again. then paint, especially anitfoul must be heavy.   then add up all tapes across joins, reinforcing double layer glass at mast, beams, plus bulkheads, fitting attachments, and you can total the whole hull ( simple to start with lw hull first). It is called a composite boat because it is cimposed of many smaller parts.   What was Rob's 3.5 kg panel weight made of?   Doug Mandurah today --- On Thu, 11/6/09, Robert <cateran1949@ yahoo.co. uk> wrote: From: Robert <cateran1949@ yahoo.co. uk> Subject: [harryproa] Re: preglassed panels To: harryproa@yahoogrou ps.com.au Date: Thursday, 11 June, 2009, 3:53 PM Have you tried the right primer on the polyprop before bogging. I have used primer to get a good grip for painting a polyprop bumper bar. Depends what foam it is cheaper than. I like it, apart from the price, for its ability to take impact. Some of the other foams disintegrate under impact and the good ones cost a lot more. It is possible to seal edges by heating, but on a long section it is too easy to stretch the edge and put the panel out of shape. . It should be possible to do about 60cm a time and nick the end of each section before heat pressing to avoid this. For internal edge finishing I was thinking of a routed out channel in a piece of timber to slip over the edge. how necessary is it to bog all the joints rather than simply putting another strip of tape to stiffen it It would certainly be easier to just use foam --- In harryproa@yahoogrou ps.com.au, Doug Haines <doha720@... > wrote: > > word of warning - polycore is a pain to work with, wherever edges join, finish or whatever happens at the edge of your panel, it's really a lot of extra work to fill all the honeycomb holes I find. Just more extra jobs/time you don't need like when it should be simple panel cut, fit in and join becomes bog all the gaps, mix extra resin and the smooth plastic honeycomb is not very grippy for the bog either. > I believe the honeycomb is cheaper by 15-20% over foam core is that right? Hmmmn...tough choice. > No local polycore in W.A., makes it same price as foam to tansport from Queensland, so I have been getting 5mm foam sheets for all the bits of stuff Lately. > Foams good for a quick poly urethane glue join together and sticking into place and you are bonded ready to get the epoxy on in not too long at all. > Just saying it is a definite shortfall of the polycoe Robert, sorry to throw you out. >   > Doug > > --- On Thu, 11/6/09, Robert <cateran1949@ ...> wrote: > > > From: Robert <cateran1949@ ...> > Subject: [harryproa] preglassed panels > To: harryproa@yahoogrou ps.com.au > Date: Thursday, 11 June, 2009, 11:41 AM > > > > > > > > > I was looking at the preglassed panels of polycore and was thinking how a 12.5mx2.5m preglassed panel could have shallow cuts on the inside of the bilge to allow bending and only need a little glassing to finish. The panels don't seem to be that much more than doing it yourself and would take some of the stress out of things and should come in at a good weight and quality being heat pressed. There may be no weight difference in the final boat. Not sure of the costs of transporting 6 large panels compared to packs of 50 small ones. 6.25 x 1.250 might be more feasible. I am waiting to find the actual price of double bias 440g preglassed to get a better comparison of price. >