revamping an old daysailer or Pimp my laser

[solrac]

hi, I have an old fiberglass sailboat 3.70m x 1.20m, something like a monosail laser but a little shorter, it uses the laser 4.70 mast system & I'm going on a full revamping...
let's explain, the hull is a bit old and has signs of delamination, well, the obvious solution, a good old jigsaw & googlesssssssss
I have taken the lines from the hull, input them on freeship, checked them back, & redrawn all again for 3mm plywood CNC cutting to make a new hull.
as drawing time flew, my volatile mind began thinking on a lot of crazy ideas, redesigning keel & rudder, a new rigged mast system for guenoa & spinnaker and so on.
the question is, would it be too crazy adding a couple of foilers to the keel?
attached some drawings...

(Solrac)
call me NUTS instead...

[gggGuest]

You need to go very very light for a foiler to work really. Otherwise the foils have to be so big that its a pain to sail when not foiling...

What I'd do in your place is build the lightest and skinniest hull I felt I could get away with and see how I went from there, and also abandon that shape completely in favour of something more modern. You want to aim for the max beam at about 70% back from the bow and have the waterlines very very nearly straight for about the first 40% from the bow. Make it hard chine for simplicity and because its faster if you sail it upright. I'd aim for no more than say 500mm max chine beam and consider making small wings rather than having flared topsides. At 500mm it will be a tippy and tricky little boat, but great fun when you get it right, and because you've only got a small rig you want to make it as easily driven as possible. Aim for a hull in the 30-40kg region no more than 4m long. Of course this does depend on your level of sailing skill! Don't worry about big sails, so much more fun to get performance with small ones.

Solrac, you might find this interesting, particularly Tom Speers comments:
Foil Assist: small or large monohulls - Boat Design Forums
Address:Foil Assist: small or large monohulls
You would probably want a higher aspect foil than you have drawn and would likely need a foil on the rudder as well.
I think there is a lot of potential in foils assisting monohulls to go faster-both with full flying and foil assist versions. The Moth foilers weigh around 220 all up with crew
and have 85 sq.ft. of sail for a sail "wing loading" of 2.58 lb.'s per sq. ft. and they are designed to foil upwind.They also have a Sail Carrying Power/Total Weight of around 33%. There is more discussion of foil assist and Bethwaites SCP/TW formula in the last few pages of the "High Performance 16 footer" thread.
One caution: just adding a foil is no guarantee of a performance increase-the design has to be done very carefully. Good Luck-I'd say study it a bit and try it!
-------------
Also, for some practical insight into sailing hydrofoils look at this forum:
Australian Moth Class Association :: Index
Address:http://www.moth.asn.au/forum/index.p...321c902664a9d2
And for more foil info check out:
www.foils.org

[solrac]

Originally Posted by gggGuest

.../ Aim for a hull in the 30-40kg region no more than 4m long. .../

I acquired this sailboat more than 20 years ago.... as you stated, it's a bit old fashion design, fatty, heavy & slow, but in my young days, I've overwalked some lasers (old times when I weighted 75kg) Jeeesuschristtttttttttttttttttttttt the hull is about 70kg.... summon my 95kg actual weight & that's the reason it behaves more like a sub than a sailboat....
sure I'm going to throw it away..... but torch-burning it first!!!
for the plywood cuts (35Kg) + fiberglass (15Kg) think it will probably raise the 50kg... the issue is not on the hull, it's on the crew weight...
About the foilers on the keel, think it will not be a reasonable idea, will complicate a lot the launch @ beach... was only a "delirium tremens" idea.
My feeling (don't know too much on the subject) think it's a compromise, for a planning speed would need a completely different hull surface/foilers size & wetted surface/crew + hull weight and a new increased rigging & sails.

Originally Posted by Lorsail

.../You would probably want a higher aspect foil than you have drawn and would likely need a foil on the rudder as well./...

I'm not trying to convince myself that an old Ford A model with new tires & new paint feels like a Mercedes kompressor..... just checking if there is something on new technologies who can do an improvement (not a miracle)
Think nobody can doubt this is an old laser type hull, it was not designed for speed planning.

thanks gggGuest & thanks Doug Lord for your comments.

[solrac]

well, as Lorsail & ggg Guest said, the there are more than a single way to peel a cat.
As usual, I'm always on the weirdest, most complicate & crazy of them.
let's see, as my "volatile" mind trying to connect some neurones, seen over the web, (don't know exactly where), a photo (first one), who burned out the few brain cells still alive here.. and heared some internal voices saying "why not?".
A couple hours later, heared the same voices, but now grasping WTF? WTF is it? (as I could'nt answer, posting here the results);
Decided that could be a nice class name: WTF450...

Now you're talking! Just add the retractable main foil/daggerboard combination with the retractable rudder and rear foil, a highspeed sock luff, camber induced unstayed main only rig, some wings or a sliding seat to get your weight outboard and voila! you've got FUN big time!
Keep the all up weight around 90lb. with a 200 lb max crew and 112sq.ft. SA and you can foil upwind; use smaller foils just to add 50% lift and you won't need an altitude control system and you'll have excellent pitch control-and higher speed than with just the hull alone in most conditions.
Go for it-what a blast!

[solrac]

well, thanks a lot for your comments Doug.
May I ask why you're for the monosail system? why not a mainsail + guenoa?
I know a stayed mast is a bit harder to camber-curve, but it's not imposible (remember snipe class?) a double sail is also a bit complicated machine, full of ropes & wires spreaded out on the deck but keeps the sail centers lower than a monosail.
I'm not trying to develop an expensive rocket for the selected high end users, the purpose of this crazy idea is developing a simple hull mold capable for teenagers at the club here to DoItYourself, (best way for kids to learn hull care, on regattas...) with some easy findable parts (laser rig+sail, snipe sails, maybe some optimist daggerboards... & so on)
One of the reasons (think the same concern out there) is keeping teens busy, clean & out of the streets with some fun for whom you won't need to invest more than, say U$S 1500.- A particular issue here is, teens, once they are 15ys, they are out of the optimist class & have few choices here, laser, snipe or get into a crew for a bigger one, so only kids with parents who can afford a one design U$S 7000 investment keep on sailing...
well, back on the theme, maybe it can be a "basic" hull with a simple daggerboard & rudder compatible with future foil sistems as the crew gets experienced?

Solrac, for your purposes a high speed sail is probably not necessary ; neither are hydrofoils. After consulting with Barry Spanier(windsurfer sail designer) and Eric Sponberg and others I'm satisfied that the best rig for a small hydrofoil(most power/least drag) is a square topped camber induced unstayed rig. There are numerous hydrofoils sailing w/o such rigs,however. And I'm experimenting with a squaretopped main +jib rig where the main has a sock luff and the rig is stayed. The jib is very high aspect ratio and the rig requires a backstay :
aeroSKIFF Wing Tip Rig™
Address:http://www.monofoiler.com/images/aeroskiff_trial006.jpg Changed:11:05 PM on Friday, October 31, 2003

I'm not sure you could do a hydrofoil in the manner you mentioned but you might be able to experiment with foil assist with the proper amount of scrounging and a bit of luck. Sounds like you sure have your heart in the right place-your idea is terrific!

[solrac]

thanks a lot, Doug
terrific design the aeroskiff, alas, it scares me a bit... for the intended purpose here, you're almost right, for begginers (if we can call beginners to 15ys old/4ys experienced optimist youngsters with a couple South American championships on their own), let's "keep it simple", as they can demonstrate expertise, (let's say a couple months/years later) well, maybe can we begin experiencing foils...
you got the idea, it's intended for a kind of experimental use... and (I hope) will be exclusively sailed for teens under a zodiac supervision.... (& some old frogs like me, on a calmy summer afternoon).
as you stated, " .../ for your purposes a high speed sail is probably not necessary/..."
wrong (sorry) that's the cherry on top of the cake, keeping in mind that you allways need a "challenge" or "tempting goal" at the end of the road to keep a teen interested...

[Rick Loheed]

I like it too! I used to have some speakers I called the BFD1000's....

Look at my hypothetical analysis of a main foil for a Moth here for ideas maybe;

http://boatdesign.net/forums/showthr...t=2447&page=34

Control is the main issue really, besides weight....

[Rick Loheed]

Say, Doug, that is an interesting rig

[CT 249]

Nice boat, Solrac.

For rig, maybe a Mistral windsurfer rig would be good? It's closer to the rig the Moth foilers use than a Laser rig is, yet it has more power than a Formula windsurfer or slalom windsurfer rig. AndyMac (who builds most of the top foiler Moth sails) said they started out very similar to Raceboard/Mistral sail. There may be plenty of second-hand sails around your area as Mistral used to be big there I think. You could even upgrade to the 8.5 and 9.5m RSX sails when they become available secondhand.

Although I've never sailed a foiler, I have raced against them on Canoes and I think a sliding seat like a Canoe takes too long to tack to work on a foiler. I think they do tighter, faster turns when the heavier sliding-seat boat takes a longer arc and that gives you time to get the seat across.

I'm certainly no expert but the world-class Canoe guys seem to take a lot longer to get across the boat than the top Moth guys (although in very light airs the Moth stops so quickly it actually loses out compared to the Canoe, surprisingly).

What sort of boat was the old hull you drew at the top of the thread?

[solrac]

nice idea, CT249, thanks, you mean, using a windsurf mast "fixed" to the hull instead of the rotating ending used on a table? Think it will overcharge the flexion moment of the mast on the deck as it would be 200% more rigid, same as a beam cantilievered one end...
I've never sailed a foiler too, my only experience is on normal sailboats, from a little penguin up to a 9mts, just thinking that for the intended use of wtf, ( a kind of easy & cheap alternative for sail school) must keep it as simple as possible, no harness, no sliding seat, even a trapeze, just a belt in the center to hold feet as body goes righting outboard.
From the "barebones" version, up to a "foiled version", everything is possible, "the only limit would be imagiation"...

[tamkvaitis]

can anybody tell me more about building tecgnology shown in the picture in post #5?

[solrac]

tamkvaitis:

just seen a couple photos over the net, think it's an old time used method.
I'll post some other photos.