Then there's no longer any advantage to buying a Blade. Of course one could cut them off as I believe that would be class legal... <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />

Anyway what is the actual increase in draft (in centimeters) with the new boards in place and did they change the location of the box?

What ? Is wider, stiffer, selftacker, better hullshape, more volume (carry heavier crews), more beam clearance, improved sails (larger squaretops), etc not enough for you ? <img src="http://www.catsailor.com/forums/images/graemlins/grin.gif" alt="" />




I think the new board are 300 mm (30 cm) longer (more draft) then the old ones. Aspect ratio is 4 and not 5 to 5.5 as with the new F18's. I think these new boards are actually a very good compromise. You are not gaining much efficiency in a daggerboard after aspect ratio 4 and with that ratio the draft is not much anyway. So these boards will still be good for singlehanding.

I seem to remember the new boards being 780 mm in wetted length (underneath the keel line). That would actually only make them 230 mm (23 cm) longer then the old ones. Let me check again.

...

Yeah there abouts. Halve of the aspect ratio gain is made by making the daggerboards more narrow.

So the difference in draft (0.55 to 0.78 mtr) is quite small. But the difference in aspect ratio is much larger, 1.85 to 4, and that makes it appear much longer.






Wouter

I haven't seemed to experience any problems with the MDF frame mould for my boat. Well, nothing I can see with my eye that I know wasn't the fault of the mould (I've made a couple of mistakes, one of which I can see until the hull gets faired.).

Otherwise I agree, for long term build projects, don't use MDF, any humidity will affect the MDF.

For a quick, one use mould (two hulls) such as I have used, I would still recommend MDF, but carefully keep an eye on the alignment.

Any new photos nick? <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" /> <img src="http://www.catsailor.com/forums/images/graemlins/smile.gif" alt="" />

Nick, did you vacume bag your boat during lay up?

I didn't use vacuum. I don't think it would be possible with the simple frame mould I used.

Photos are being taken all the time, but parents have stolen the camera.

I would really like to see some more pictures because I plan to build mine the same way.

Do you think you will be close to minimum weight? What kind of problems have you ran into and how do you plan to build the deck and how to attach it?

Hopefully will be on weight but might be 1-2 kilos over, depends on what rig is on it. The hulls are in the ball-park of the weight range.

Lots of problems, no major ones. Do a search for my posts on this forum to read up on these problems further. You're gonna have to be prepared to problem solve on-the-fly when building a boat.

Deck is on, it was a simple, flat deck glued on with cured glass on the underside held down with weights. When the glue had cured, a glass skin was applied to the outside from gunwale to gunwale which nicely accounted for the glass deck join too. I was concerned it would look crap but it was very simple and it has come out really well.

Be prepared to buy a good grinder and plenty of sperm suits (I don't know what their real name is, they're just white disposable overalls.).

I am still having trouble picturing this deck but I think I have the idea but what were you gluing it to?

I am ready for problems and don't mind having to figure them out.

Did you think about using carbon or kevlar around the known problem areas, like the beam seats and just in front of the forward beam?

Now that's a broad oops I mean board that really appeals to me Wouter (especially the one in yellow)

There was a timber flange glued around the inside edge of the gunwale before the deck went on.

The beam mounts are carbon, sort of (you'll see in the photos when I finally get them uploaded). Both natural and synthetic...

I considered carbon reinforcement in certain areas of the hull and deck for stiffness (rather than strength), but my composites engineering mate informed me that it's better to use carbon globally rather than locally, particularly in cored construction. Carbon is so stiff that it takes all of the load, so the rest of the laminate does nothing. Worst case scenario is that the amount of carbon laminated into the composite isn't strong enough and the whole laminate fails. Without knowing the design loads more thoroughly, it wasn't worth the risk. I don't like working with kevlar. Cost was also a factor, otherwise I would've gone with carbon throughout.

So, Carbon built like this is possible also? I have a fairly cheap source of carbon fiber cloth and have been thinking about using it instead but I wasn't sure if it was do able.

I have heard the argument about the carbon taking all the load also so I assume that if you can't build the whole thing out of it, then none is a better choice.

I am very curious to see your other pictures since your building is basically what is inspiring me to build my boat.

Was thinking in that direction for the F12. More and more it appears like you are piloting a building method that could be directly applied to a relatively simple method for homebuilding F12 hulls while still ending up with a nice looking and sufficiently modern hullshape.

Keep the info coming please.

Wouter

Darryl,
Yep, I'll have one of those.

Gree
You can use carbon if you just keep in mind that it will take all the load because when loaded the glass will be more elastic leaving the carbon to do all the work.

Taking this into account you can use it to distribute the load over a wider area in the glass laminate.
However if you don't engineer this properly you could have problems.

Regards,
Phill

Whats that little nub about a foot or so down from the top of the board on the outboard side for?

Patrick,
Are taking about the recess in the board for the knot in the pull-up line which goes thru a hole in the board from the inboard side.
This should be about a foot and a half down from the head of the board.
The recess is just so the knot does not jam the board when it's in the case.

thanks Phil. That makes sense. I didn't know these boards had lines to pull them up.

Could the chainplates be built into the hull during the layup rather than attaching them after?

This build technique could work with any size cat right? I mean up to a certain point but anything under 20 feet? It doesn't seem like it will be as much works as building a ply boat, but I wonder if the results will be as good. I mean Ply boats win alot of races, so will this boat be able to?

Also how many layers of fiberglass did you use on the inside and outside?

Hey guys, before you get all excited about this foam build method please consider that those building the home build Farrier boats, have been building exactly like this for a lot of years, they have ironed out the problems, so before you start reinventing the wheel perhaps you may want to consider getting a preliminary study pack from Ian (www.f-boat.com/), it may save you a lot of time.

As to Carbon fibre chain plates, again this is standard practice with the Farrier designs, but I do stress that it may not be so practical for our requirements with the knocks and bangs we get, launching and pitch poling etc. Carbon has a tendancy to be "brittle" ie bend it and it breaks terminally where as bend glass and it will bend to a point, then splinter along the fibre, but will retain some of its previous strength.

What is the big deal about Carbon anyway, if you lower the cloth weight ( in boat building hull terms )to a point where you are saving weight then it simply cannot meet the impact loadings which almost certainly a beach cat will take.

You are far better off to build the hulls with good quality EGlass and Epoxy resin. Put the financial savings toward a Carbon mast and then skip lunch and beers for a few days, you will save far more weight, have a far more robust boat and be fitter and lighter for it. <img src="http://www.catsailor.com/forums/images/graemlins/cool.gif" alt="" />