Kon-Tiki

Having a break from Planes, after severing 2 fingers on my left hand while running-in a new RCV-58 4-stroke, I fancied making somthing that's powered by the wind!

I've built half a dozen real "Full size" yachts using GRP and have always wanted a Wharram Polynesian Catamaran. So that's what I desided to made a model of.

The Hulls are made using my "Misers Dream" fast build philosophy using Corro (just like SPAD Planes). I can get two 48" long hulls from one sheet 4ft X 3ft. After folding and gluing the ends, the middle has to be opened up and a few bulheads inserted. On the first attempt, the CA glue joint came apart. I removed all the glue with sandpaper, Acetone and re-flashed it. Second attempt seems to be holding. There really is a lot of stress at these points. The front and rear seams have a thick fillet of silicone bath sealant on the inside to keep the water out.

The two wooden strips - rubbing strakes at the gunwhales stuck OK and the decking will be glued to them and to the top of the 3 . Should then be a nice strong structure.

This heres the pair of hulls ~ just a few hours work:

Kon-Tiki

Bulkheads in and deck on:

RobStagis

If you take a look around, there's a new claass of multihull, F48, that's pretty starwars. Also www.microsail.com has some spaceage thingies. coroplast might be the ticket......

Stoopid question, because I just heard of SPAD's a few months ago - what's 'flashing' the material, please?

RobStagis

I apologize - nice design on the hull!!! Forgot to mention it earlier. Others might disagree, but I recognize 'em - excellent!

Kon-Tiki

Hi there. It's almost finished! Could have made Her in a week but I'm working mostly with one hand at the moment.

I looks at microsail but could'nt fin the Catamaran. Only Tri's. I'll have another closer look later.

Yes it's very much a Wharram Cat, very much like a Tiki 21, except it will have a "Bridge-deck Cabin" to house the radio gear. I made the Mainsail from a plastic garbage bag and will make a Jib later today. All being well, off to the boating lake next week.

I still need to make & fit the rudders, hatch tops, netting and fit the radio gear. I'll leave the cabin until I've had a trial sail!

Kon-Tiki

RobStagis

Oh, sorry FLASHING
Corro (Correx in the UK) has an oily deposit on the surface which is produced during manufacture. It's hard to remove and if left on the surface, there is no type of glue which will stick to it. You can:

You Flash the surface with a blow-lamp! You have to move the flame over the surface quite fast or you'll melt it. You can practice on scaps of Corro until you've perfected it. It's no major hassle after a while. The surface goes a little "wet" lloking and then it evaporates. Then clean over the area with acetone. You can then stick Corro using CA glues.

When I made my Hulls, they had a tendency to want to "spring open" at the ends. I solved this problem by epoxying the wooden rubbing strakes together at both sharp ends. I tried to pull the test hull apart but just tore the Corro!

RobStagis

Sorry - microsail doesn't have cats. There's come sort of technical numbers that state that tri's are faster and easier-tacking. *grin* Good job!!!

And thanks for the 'flashing' tip. I've got a couple C/L planes (Plastic Funtasticks by Mike Ogren) that use coro tail surfaces, and maybe with this tip, they'll stick together

Rob

Kon-Tiki

Had a good look at MicoSail's website. Some very interesting innovations. They work in association with Graham Bantock - SAILSetc who are in Kelvedon, Essex, UK - 2 miles from here. Never knew they were there! Rather than keep taking pictures, I working to finish off my boat. Hopefully Monday or Tuesday it'll be complete and . . . . just remembered I need to order eight AA NiMH batteries for the TX!

Kon-Tiki

Just the Cabin module to make, Hatch tops and Jib sail:

http://www.skylites.freeserve.co.uk/kon-tiki/

I fancy making a "Pirate Ship" version next!


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RobStagis

Woohoo!!! Gave it its own website!!! It looks great!

Kon-Tiki

I've moved the website to: http://www.kon-tiki.freeserve.co.uk/

Just awaiting a more powerful servo for the sails to arrive and then off to "Sea Trials" !

rcsoar4fun

My Feedback: (12)

Have you had a chance to take her sailing yet? Sometimes I think a Wharram design is just what the r/c sailing world needs. A suggestion on the bonding of the Correx, you might look into some stuff called "Shoe Goo". Its used to reattach soles to shoes. Its also uses as a general around the house adhesive. It remains slightly pliable and bonds like crazy to correx.

Kristopher

http://www.rcmultihulls.com

Kon-Tiki

Hi rcsoar4fun

Taking Kon Tiki for "Sea Trials" on Wednesday. I have been waiting for all the Children to go back to school as the lake is full of kids fishing, paddling, and thowing stones! The signs say" NO FISHING" "NO PADDLING" "NO DIVING" ! it's only 3ft deep!

Not seen Sho Goo but there again I am in ther UK. We have a sho repair shop up the road. I will ask. They may heve something similar I can try.

Believe me, if circumstances were different . . . . as my Wife tells everyone, I'de be building a 40 footer! However, this is fun. Already planning a "Pirate Ship" schooner version and some bigger boats! God, I hope it sails OK.

Kon-Tiki

Still waiting for blocks to arrive . . . . can't wait any longer! I've now set up the "Sail Winch" and used "Brass Eyelets" in place of pulley's/blocks. The drag is actually very low. The JUMBO servo could move a house.

Grand Launch is on Wednesday!

Kon-Tiki

Close-up picture showing Mainsail sheet

rcsoar4fun

My Feedback: (12)

On my 1m soling I have used sliding door hardware in place of blocks. They are used as rollers on the bottom of screen and glass doors. A pair is about $2 for a ball bearing raced set. They fit perfectly on a winch arm. I will try and take some pics if anyone is interested

Kristopher

Kon-Tiki

Kristopher (rcsoar4fun)

Please post some picture if possible. I constantly spend hours in our local DIY stores looking at all the "Bits-and-pieces". I will look at sliding-door gear next time I am there.

It used to be easy to pick up small brass or plastic pulleys. I've sent numerous emails and if I get an answer it's normally been negative.

This boat is so easy to modify. I even have two central deck units with different servo's. I have some information coming on converting an electric (cordless) screwdriver as a "Drum" type sail-winch!

Bye for now . . .
more updates on website: www.kon-tiki.freeserve.co.uk

Kon-Tiki

Today was launch day. Kon Tiki sails very well, infact Her performance is excellent!

Few slight problems requiring modifications:

Kon Tiki turns very slowly. The Rudder surface area is too small. Rudder Needs increasing by 50%.

The 3 halyards are of thin yacht rope of the non-pre-stretched variety. The sail geometry completely changes with high wind loading. Need to be replaced with cycle brake wire or pre-stretched rope.

Kon Tiki although a large boat, is very light in weight. Perhaps too light. In strong winds she still sail straight and with little or no tendency to capsize. However She want to nose dive into the water thus bringing the aft end out high and also with little rudder left in the water. Reluctantly, I will try adding some ballast. None was actually require to trim her as she sits perfectly in the water.

Any suggestions on this point will be most welcome.

Latest updates:

http://www.kon-tiki.freeserve.co.uk

Kon-Tiki

I've been having so much fun with Kon Tiki, that I've not been on here lately or up-dated my website for a while!

Anyway, She sails like a dream . . . . but like most Catamarans is hard to tack thru the wind! She is VERY fast and jybes well. I've now made a cabin and although fitted, still requires windows to finish Her off.

RobStagis

What I've seen is that we tend to overbuild our boats. For instance, last year my Robbe Atlantis tipped off its stand and broke all the port-side stays *sigh*. That night, having only 20-lb. leader material, I re-rigged with it just to finish out the season. While I didn't take it out in hurricane winds, I did sail it up to about 25mph winds, which is a lot, eh? Didn't break a stay, though my heart was in my throat. Over the winter I re-rigged with 40-pound stuff.....

Anyway - kite line (spectra, Dyneema) is one source for non-stretching halyards. It goes up to 200-pound test! It stretches a little, but you can also pre-stretch it, or rich folks can buy it pre-stretched. We're not talking a lot of stretch here, since the kite guys want the same length lines over 100 feet or so... Or (in the States) we have Spyderline from fishing shops. Again, it goes up to about 80-pounds and doesn't stretch at all. (or enough to talk about). Cheap and you get a lot of it on a reel.

Diving under 'power' is pretty normal - witness the bulbous bows on some model sailboats. These 'expansions' are there to keep the bow up. With twin hulls, you've got more drag under there. My Star 45 was virtually unsailable with my original, totally yucky bulb. After I cleaned the bulb up, it sails well and keeps its bow up except under the most extreme (read: stupid-to-sail-in-these-winds) conditions.

Move your batteries way back? Move your servos back, if possible? Does that thing have daggerboards? Make 'em skinnier, clean 'em up, make 'em smaller? (If it has 'em - I don't remember). A drastic step would be to expand the bows, or make a wee 'foil' under 'em.....

Have fun

Kon-Tiki

RobStagis

All noted. Yep, always gone for the "Overkill" . . . your absolutely right. There are things on my Boat and Planes that are strong enough, thick enough and cost more than on a full size one!

Most of the nylon/terylene ropes here locally are NOT pre-stretched. I purchased some 2mm stuff from a builders supply store and used it for eveything on Kon Tiki. It stretches like Hell! I have discovered a local company called SAILSetc just 2 miles up the road! amazing, as we live in a small village in the middle of NoWhere. This company make 1mtr racing Yachts and make or buy in every component you would ever need. Blocks, cleats, even raw material for masts and all the fittings. I will pay them a visit shortly. Infact, I think I will take Kon Tiki with me and see what fittings together with Catalogue numbers and prices, they have suitable for the boat.

Well, Kon Tiki is almost there . . . . what next? I was going to make a 6 or even 8 footer!!! BUT I have enough material to make a 2ft mini version. This will be able to use a standard servo for the sails!

A freind of mine has asked me to make a tri-maran version . . . will it sail closer to the wind ? . . . . . . . Will it Tack better through the wind ?

RobStagis

You just found out you live next to SailsETC? They're all you'll ever need. I do tend to frequent fishing-supply stores, though - lots cheaper. That SpyderWire (or Line, or whatever it's called) is good stuff. Limp, takes knots well and it's thin as hell - runs through blocks just as nice as well...whatever. Reduces friction in running rigging, but tends to wear a little - but the wear is obvious: it changes color and you can see it.

Send your pics to MicroSail's owner. He's a dyed-in-the-wool multihull freak, even if his boats are way high-tech. He has opinions on cats versus tris, and he might be able to help with design issues. Tell him I sent you . We've agreed to disagree - he's in love with high-tech stuff, and I'm a traditional-boat nutcase.