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Old Jul 29, 2011, 09:38 PM
slow & draggy...
Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
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24 inch laser scratch build

Ive been kicking this project around for years in the back of my head, finally got around to doing something on it. I always wanted to build an RC laser like the retro early 70s one i owned n sailed at the lake as a kid, and didnt really have the $600 or so to get a new RC laser class boat (although they are impressive) plus felt an experiment would a whole lotta be fun if i could scale it down a little and build it out of fairly inexpensive materials having it look as close to scale as it could be as an RC model, and from what i could remember of my beloved 1st vessel from childhood....

Built from dense owens purple insulation foam from Home Depot, 1/8 wood deck. Foam sanded and sanded to shape then glassed w several coats of epoxy, filler... and did i mention? alot of sanding! Sail is a just a prototype made from ripstop nylon tensioned down as well as possible, but i just
got some quality poly and higher tech film ordered that im going to experiment with as well.

Ready for a maiden this weekend- Only thing that has me a tad worried is if keel bulb might be to heavy for the ammt of water she will displace, and i could end up having to cut the existing one off and fabricate another lighter one.

I used the top and side view drawings of the original laser and just did a vector trace in Illustrator and scaled to 24" for the templates so deck, sail shape and mast height would be as scale to the real boat as possible. I do have the vector saved as a PDF and alot of pics of the build process if anybodys interested in seeing them - i think this little guy really has the potential to be a fun little model if she floats, and sails halfway decent.

looking forward to the maiden nonetheless and seeing what she does on the pond this weekend
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Old Jul 29, 2011, 11:05 PM
Taking care of the pond.
MILLERTIME's Avatar
USA, CA, Fresno
Joined Apr 2004
7,323 Posts
Looks good.
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Old Jul 30, 2011, 02:49 AM
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Blackpool, Lancs
Joined Feb 2006
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Looks the part - I think you are right about the bulb though, while it will be all but impossible for any known wind to knock it over, it will sit far too deep for performance. Think in terms of about 1lb max, and a more pointy shape. The 4' lasers draw about 18", it looks like yours does as well, reducing it to about 12" would improve performance by reducing drag.
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Old Jul 30, 2011, 10:56 AM
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United States, DE, Lewes
Joined Dec 2005
398 Posts
Hobie,

I agree with mfr02 - the 2 lb. bulb & the long keel are probably overkill. A shorter keel & lighter bulb should work better.

I have a Lareke RG65 - build thread here -

http://www.rcgroups.com/forums/showt...ghlight=laerke

My Laerke is similar in size to your Laser(650 mm - 25.5"). It's all up weight is 2 lb 7 oz & the keel length including the bulb is 10.5 in. The bulb is a 1 lb. fishing weight. If you look at the pix of the boatin the tub in my thread you'll see that the boat sits at it's designed water line at the above weght.

Good luck with your 1st sail. You did a great job with your Laser - it turned out looking great!!
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Old Jul 30, 2011, 11:40 AM
slow & draggy...
Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
Thanks for the input guys,
I definatley agree if the bulb is too heavy ill know right away, but making another one would be fairly easy. I cant really tell how heavy the thing is until i get a new scale, but hoping its only 1.5lbs or so and the beam of the boat will be wide enough. perhaps thats wishful thinking haha but in any case i should know later this afternoon.

Also the length of the fin from the bottom of the keel bulb to the bottom of the hull is only 10.75 inches, the pics i think are making it look longer but thats the actual length of the fin and bulb and the fin width is 1.5 inches, so i think im where i need to be with the depth of the keel, just unsure bout the bulb weight. Should be pretty easy to tell if ill need a new one when i drop her in the water, will definatley aim for a 1lb bulb if she draws too much at the waterline.
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Old Jul 30, 2011, 11:56 AM
slow & draggy...
Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
i need to get a scale, just tried a low-tech approach of comparing weight of boat to a 4lb bag of dog food, the dog food definatley feels much heavier than the weight of the boat, so im guessin overall weight of boat to be in the 3lb range or so(?)
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Old Jul 30, 2011, 02:14 PM
slow & draggy...
Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
Ok, so my curiousity got the best of me and i dug up a big tub and filled with water to play an imprompteau game of "will it float?" Turns out i just suck at estimating the weight of things as she really floats well and the waterline is maybe only .5in from the bottom of the hull happiliy enough. So most likley the weight of the bulb and whole boat is probably much less than my original estimates, maybe in between 2.5 and 3 lb range overall. hoping for a really good maiden now, just hopin rain doesnt move in....
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Old Jul 30, 2011, 10:29 PM
slow & draggy...
Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
Happy to report she sails very well Wasnt much wind out there but there were a few gusts that got her moving pretty well, i was actually quite surprised that she did so well keel weight whatever it is works fine, a few gusts up to like 20mph were a bit too much for her and she would heel over and temporarily lose control, but that was only in the big gusts, she can sail well ideally in winds inbetween 5 and 15mph.
Performs nearly as well as my blackhawk 32 from victor models. Able to tack extremely well in light winds. Overall very happy about this boat! Since ive got alot of foam and materials left over from this build, i will keep this one the way it is, and build another and experiment with making a keel bulb roughly the same weight, but "more pointy" on the ends to see if that affects performance any... thanks for the input and advice, gonna have a blast with this boat!
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Old Jul 31, 2011, 02:24 AM
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Jersey,C.I. (GB)
Joined Mar 2008
172 Posts
There is always this:

http://shop.traplet.com/product.aspx?c=1584

if you want to get serious about best ballast profile.

Edward.
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Old Jul 31, 2011, 03:13 AM
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Could try something like this

http://www.mm-sailing.de/mm-hp/links...elgewichte.htm
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Old Jul 31, 2011, 12:48 PM
slow & draggy...
Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
Thanks Werlec Edward and waboats - You know after looking at those links u guys sent, i think it does make perfect sense and would really give a big performance boost if i went with a more efficient bulb shape like the ones you reccomend - i looked into these threads and yes those shapes are really where i need to be. I went ahead and ordered some nice 1lb fishing weights and im going to do as werlec did on his beautiful Laerke RG65 (that is one GREAT lookin boat btw! ill prob have to do one of those real soon now and use someTSp40 on it) Ill shape the back as well as front of the fishing weight w bondo and sand the whole thing real smooth to have a very nice shape and go from there, i may try the mold casting method as well. i spent alot of hours on this baby, might as well do her right, and learn something in the process...Plus im sure i will be surprised at the performance boost over the current torpedo shape and size Thanks a million!
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Old Jul 31, 2011, 07:12 PM
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United States, DE, Lewes
Joined Dec 2005
398 Posts
Hobie,

Your boat looks great on the water! You should get a lot of sailing enjoyment out of her. She looks just like to "big" 48" ones. When I was in Marco Island Florida in March this year they were having a Laser model regatta. It was really impressive seeing 8 or so of them racing at one time. Like a dummy I didn't have my camera that day, so I didn't get any pictures of them.

I was able to sail my Laerke down there though. They had a great facility to sail on(Mackle Community Park) - plenty of breeze - too much for my boat some of the days.

One advantage of the small boat was that I was able to take it, my golf clubs and all of our other stuff to Fl in our Prius

Thanks for the kind words on my Laerke - the folks on this forum were a great help on my 1st build. I'm thinkin' my next build is going to be a J-boat of about 36"

Happy sailing,

Erle
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Old Aug 01, 2011, 07:06 PM
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Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
Last night i was thinking of the mold method and how it was something that sounded like it was too much fun not to try, so i was looking at the small bulb i had cut of my Discovery 500 - and got the idea of using it to make a plaster mold to pour melted lead into. when you look at the tapered end, it seemed if i made a mold of 3/4ths the length of the original bulb, then made 2 lead positives from the mold, fix both havles together, and i could end up with a very nice shape and weight for the laser keel. the mold really is pretty easy to make, i just cut the top from a coke can, filled with plaster, used original bulb harvested from the Discovey to acheive the shape, and hung it into the mix about 3/4ths the length of the bulb so the tapered end would become my mold.

Used a small propane blow torch to melt several lead fishing weights in the bottom of a steel can carefully and poured the hot lead into the mold - got the following result after drilling holes in both lead positives, and using a steel rod between, epoxied it all together. Sounds like alot of work but really wasnt all that bad. Its smaller than the original yet a tad heavier and a much more efficient shape than the girthy torpedo thats currently on there. Going to cut length of fin down an inch as well when i mount the new bulb. Hoping for even better performance and much less drag.
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Old Aug 14, 2011, 11:19 PM
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Canada, BC, Victoria
Joined Mar 2004
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Your boat looks super! I tried a friends boat this weekend, and it gave me the inspiration to see about making one also. How did shape the hull? I know you did a lot of sanding, but how did you know what the right shape was?
Colin
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Old Aug 15, 2011, 01:39 PM
slow & draggy...
Hobiestoke's Avatar
Albuquerque, NM
Joined Jul 2004
463 Posts
Well, this is basically a scale model of the boat i owned as a kid. loved that thing and have loved lasers for many years so the hull shape is embedded in my mind pretty well. Also i drew a vector side/top view based off the original drawings of the fullsize real laser so it would be scale to the original, once i had a good vector drawing I simply scaled the whole thing to a 24" length, and printed the deck out on 2 sheets of legal sized card stock to use as a template to cut out the 2 layers of purple insulation foam and deck, then shaped from there, its really not all that hard once you start digging in, basically just rounding down the sides and using the drawing as reference for hull shape and "sculpt" it to shape w sandpaper. the 3 or 4 layers of epoxy and filler make it as solid a surface as plastic once your done, basically not all that much different from how surfboards are fabricated....

Im actually planning on building another very soon but out of fiberglass, so im going to really take my time on this new hull shape & once i have a perfect glassed foam hull im going to use it to make a master mold so i can lay up the 24in laser hulls in actual fiberglass - more to come on that soon as im just now learning the process. I will post vector drawing and some build pics that show the foam shaping process later tonight, the build on this boat is really alot of fun and she sails suprisingly well. I will be modding on a much better shaped keel bulb to my prototype that has a much slimmer profile this week and will post pics of that as well
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Last edited by Hobiestoke; Aug 15, 2011 at 10:07 PM.
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