G'day,
Me and my big mouth! Notice the "at this stage". ;-). Pretty easy
design brief though. Faster than anything else out there, big and
comfortable enough for a big guy to cruise solo, dead simple to build,
trailerable and must not capsize.
Crew weight and payload 700 lbs/320 kgs (I have to work weights in
kgs or make some embarassing mistakes, 2.2 kgs/pound)
Boat weight 900 lbs/410 kgs
Sail area for BN of 2 = (assuming empty boat), SA= 370 sq'/34 sq m.
Assume 5:1 aspect ratio, boom length is 2.6m, luff length is 13m.
This assumes a una rig. It is not possible to (easily) telescope an
easy rig. Thinking about it, it is not so complicated, but the loads
will increase. Maybe have a 3/4 height jib, which is removed for the
1st reef, then telescope the top quarter of the rig for the second
reef. Although for sailing in 5 knots of breeze, height is king, so
the una rig is probably a better bet. Worth some more discussion, I
think. Definitely a wing section, either way.
So far, so good, now the tricky part. No capsze. Not sure that I can
guarantee this. That is a big rig on a little boat. I will pass
responsibility for this requirement back to you and your sailing
ability.
Files are now open again.
Assuming the dimensions and calculations are correct (I rough checked
a couple and they were), the drawings look good. I assume you have
drawn it in the other view and 3d to be sure it all fits. If
possible, I would extend the lee hull length to 35', and leave out the
kink in the topsides.
Righting moment is 300 kgs at 4.25m (not quite correct, but near
enough) = 1.275 tonne metres, which will need a decent bury for the
mast, or a stronger lee hull. You can either pay $aus1,000 to have
this engineered, or go with my gut feeling, which I will post you off
list with the usual cautions and conditions. I would advise the
engineering.
Easiest build is flat panels, partially or fully glassed with glassed
polystyrene in the compound curve areas outside the beams, below the
water. Either I can calculate the panel shapes, or you can and send
it to me for comments. The deck can either have a deck edge radius,
or you can use a timber stringer and glue the hull and decks to this,
round the edge and apply a layer of external glass. Easier and
quicker, but not as rounded or as neat as the der. You should be
able to make the deck panel pretty accurately, but no big deal if it
is a little bigger. Adding rebates to areas of the panel where there
will be joins will make it neater/less fairing.
Telescoping beams are tricky. They need to be a tight fit when out
and a loose fit for sliding. Plastic over pvc pipe will not release
if the whole thing is laminated on it. Lay up your internal skin with
a piece of plastic under the 2" overlap. When cured, remove the skin
from the pipe, then glue the overlap so it is a loose fit on the pipe.
Then layup the rest of the laminate. Build up the ends for the
tight fit, the rest for a loose fit, fair it and use it as a mould for
the other half beam, building it the same way.
Telescoping beams are easier to build as square sections as you can
work on the inside. Again, you have the choice of engineering the
beams or going with my gut. More on this off list.
Anything else, let me know.
regards,
Rob
On Wed, Mar 25, 2009 at 11:23 PM, Gardner Pomper <gardner@networknow.
> Rob,
>
> Ok, you asked for it! <grin>. I haven't moved this to a new thread, but
> maybe I should.
> These questions are all based on the camper files I uploaded to
> Files->Gardner'
> moment, but hopefully that is a temporary problem.
> First, the purpose of the boat is to be a long distance single person
> cruiser. I want to do the same type of thing that Doug is doing with his,
> but I probably weigh twice what he does and have a higher minimum comfort
> level, I expect. Secondary purpose is as a fast, fun daysailor for the
> family (2 adults, 1 child, total weight 550 lbs). But, I do *NOT* want to
> capsize. I don't want to fly a hull. I want relaxation at speed, not
> adrenaline rush.
> As I have mentioned in prior posts, we live in an area of light winds.
> Summers here often have winds light and variable, 5 kts or less. Over 10 kts
> is uncommon. Over 15 and I don't go daysailing. Because of all this, I want
> a large sail area that can be easily reduced to cope with higher winds. I
> also want to be able to sail in 30+ kts, for those times I am cruising and
> get caught.
> The primary building characteristic of the boat must be simplicity. I have
> no boatbuilding experience and want something forgiving. To this end, my
> concept for this boat is that it can be built in 3 major sections, lw hull,
> ww hull and deck. The idea is to build the deck first, as it is simplest and
> least important to the structure, which will give me some experience before
> I tackle the hulls.
> One last thing; ignore the bicycle pedal idea for now. I may go with a
> sculling oar and/or a portable electric outboard. That is all undecided and
> I don't want it to hold up the rest of the boat.
> Questions:
> 1) I figure an empty weight (all up) of 200 lbs per hull, 200 lbs for the
> deck, 100 lbs for rig (guess), 100 lbs for crossbeams (guess) and maybe 100
> lbs misc, for about 900 lbs. Payload about 700 lbs (150 lbs equip + 550 lbs
> crew for daysailing; 200 lbs equip, 300 lbs crew, 200 lbs stores for
> cruising). Does all that seem reasonable, given the measurements in the
> drawing?
> 2) 3/8" core throughout, except for horizontal deck surfaces wehre I walk.
> Use 1/2" there. 6oz fiberglass everwhere, except under the waterline, where
> 18oz for grounding protection. All ok?
> 3) Build telescoping beams by wrapping carbon fiber around PVC tubing
> wrapped in plastic sheeting and vacuum bagged. Slide the PVC tubing out
> after resin sets. What diameter tubing should I use? should I wrap carbon,
> then wrap foam around, then another layer of carbon, or just 1 thick layer?
> I seem to be able to get 12 oz carbon fiber twill reasonable cheap ($26/yd
> in 47" width, so just over $2/sq ft).
> 4) If I can still get it, there might be a few sheets of 3/8" airex
> available at about the same price as corecell. If I just use it for the keel
> sections, I figure I can cut 2'x8' pieces for teh keel and use 4 pieces for
> the lw hull and 2 pieces for ww hull, so just 3 sheets of it. That should
> allow me to make the 4" radius bend in the ww hull and 6" radius in the lw
> hull.
> 5) When I get to the rig, I want to look at your ideas for a telescoping
> mast. That sounds appropriate for the light wind days, and I can just keep
> it down on days with more wind and reef when it gets really windy. I have
> not done the calcs yet for bruce number, but I would like to get close to a
> 2 when loaded for sailing.
> 6) I would like to start building the deck first. Given my idea of just
> dropping it on top of the ww hull, I am assuming that we can make minor
> changes in the hull specs without my having to redo the deck. I was not
> planning on having the hull/deck vertical transition be seamless; I was just
> going to make the deck rectangular and let the corners stick out, to
> simplify building. Do you think I can get away with that?
> 7) What would you change in the design, given my requirements?
> Thanks,
> - Gardner
>
> On Wed, Mar 25, 2009 at 6:13 AM, Rob Denney <harryproa@gmail.
>>
>> G'day,
>>
>> My Elementarry is 3mm foam with carbon each side. 10mm/3/8" will be
>> heaps for yours. Flat floors on ww hulls hit with a bang after a
>> capsize. Definitely 18 oz either side. Airex wil do, but it is very
>> expensive. I'd persevere with the Core cell.
>>
>> No need for any money at this stage. Ask questions, I'll answer. I
>> am away for 2 weeks from next week, so ask before Sunday, please.
>>
>> regards,
>>
>> Rob
>>
>> On Wed, Mar 25, 2009 at 12:14 PM, Gardner Pomper <gardner@networknow.
>> wrote:
>> > The pipe idea is a good one. I may try that on a small piece.
>> >
>> > This is all for my sidecar for fat people version. I was thinking of
>> > using 6
>> > oz everywhere, except under the waterline, where I was going to use a
>> > layer
>> > of 18oz. Since that is where the bend is, I guess I need to do more
>> > testing
>> > with the 18oz.
>> > Another possiblity I have considered, and is getting more attractive, is
>> > to
>> > get some Airex foam for just the highly curved sections. I was thinking
>> > of
>> > the ww hull with a 12" flat floor, and a 6" radius curve up the sides.
>> > If I
>> > use corecell for the flat section, glued to 12" strips of airex, then
>> > glue
>> > more corecell up the sides, then I should be able to bend it. I had a
>> > lead
>> > on some 3/8" airex a month or so ago that I didn't follow up on, so I
>> > don't
>> > know if it is still available.
>> > I think it is about time that we talk about how I hire you for some
>> > design
>> > work on this. I don't want to buy 3/8" airex, if I need 1/2". I just
>> > need
>> > something preliminary. Or, I can just wait until I have the topsides
>> > built,
>> > but airex is harder to come by than diamonds nowadays.
>> > - Gardner
>> >
>> > On Tue, Mar 24, 2009 at 10:20 PM, Rob Denney <harryproa@gmail.
>> > wrote:
>> >>
>> >> Sound good to me. I would do some more little panels first. If they
>> >> will bend, then the big one should not be a problem. Could also use a
>> >> 6" radius pipe to bend it over. Is 6 oz the laminate you will be
>> >> using on the boat? If not, use whatever you will be using.
>> >>
>> >> regards,
>> >> rob
>> >>
>> >> On Wed, Mar 25, 2009 at 10:17 AM, Gardner Pomper
>> >> <gardner@networknow.
>> >> wrote:
>> >> > I tried bending it by hand and it bent unevenly, almost like a
>> >> > crease.
>> >> > If I
>> >> > was bending it over a mold, then maybe I could use tiedown straps or
>> >> > something and just tighten it once an hour or something. This was a
>> >> > small
>> >> > (3"x12") sample piece I was just bending in my hands. I didn't really
>> >> > want
>> >> > to waste a whole panel trying something bigger. If I do a 4'x8'
>> >> > panel,
>> >> > should I just hang it with straps from the ceiling and pour in sand
>> >> > or
>> >> > something to weight it down? Add more sand once and hour or
>> >> > something?
>> >> >
>> >> > - Gardner
>> >> >
>> >> > On Tue, Mar 24, 2009 at 8:46 PM, Rob Denney <harryproa@gmail.
>> >> > wrote:
>> >> >>
>> >> >> G'day,
>> >> >>
>> >> >> Surprised you needed to cut it for a 6" radius. Slow, steady and
>> >> >> even
>> >> >> pressure which evenly crushes the foam on the compression face
>> >> >> should
>> >> >> have done the trick.
>> >> >>
>> >> >> The depth of the cuts is trial and error, dependant mainly on the
>> >> >> radius of the curve and the foam thickness. Deep enough so it bends,
>> >> >> shallow enough so it doesn't show on the outside.
>> >> >>
>> >> >> More, shallower and thinner are best, but time consuming. You should
>> >> >> also make sure all cuts are filled with bog before folding
>> >> >> otherwise,
>> >> >> if water gets in (usually through a skin fitting) it travels along
>> >> >> the
>> >> >> cuts and eventually gets a bit smelly and messy.
>> >> >>
>> >> >> regards,
>> >> >>
>> >> >> rob
>> >> >>
>> >> >> On Mon, Mar 23, 2009 at 12:58 PM, Gardner Pomper
>> >> >> <gardner@networknow.
>> >> >> wrote:
>> >> >> > Hi,
>> >> >> >
>> >> >> > I am experimenting with vacuum bagging and resin infusion for the
>> >> >> > first
>> >> >> > time. I am trying to figure out how to bend the foam. I have tried
>> >> >> > 2
>> >> >> > pieces
>> >> >> > of corecell, one 1/2" and one 3/8", both with 6 oz fiberglass on
>> >> >> > one
>> >> >> > side. I
>> >> >> > tried using the circular saw, and cut 8 grooves 1" apart, 3/16"
>> >> >> > deep.
>> >> >> > This
>> >> >> > allowed me to bend the pieces into 6" semi-circle, but the foam
>> >> >> > creases
>> >> >> > and
>> >> >> > you can see the fold lines on the outside of the fiberglass; it
>> >> >> > isn't
>> >> >> > a
>> >> >> > smooth curve.
>> >> >> > Is there some information on how to do this with corecell? I have
>> >> >> > a
>> >> >> > older
>> >> >> > booklet that talks about airex, but it is bendable.
>> >> >> > Should I be cutting thinner grooves than a circular saw blade?
>> >> >> > Closer
>> >> >> > together? Deeper? Shallower?
>> >> >> > Thanks!
>> >> >> > - Gardner Pomper
>> >> >> >
>> >> >
>> >> >
>> >
>> >
>
>
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