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Author Topic: Mini speedboat project  (Read 17416 times)

Andy M

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Mini speedboat project
« on: May 02, 2006, 01:48:18 PM »

For a few years now, I have wanted to build a Lesro Javelin,but never got round to it,lack of a marine engine helped keep the project from starting. Then my friend and I were talking one day and I mentioned that I had always wanted to build a Javelin,but had no engine.He told me he had a Honda 8 HP generator engine,why not make one to sit in.I have already built a yacht scaled up from Vic Smeed's Starlet,but now I feel the need for speed.I messed about with Photoshop and put meself in the picture so to speak. The first attempts made the boat too long to use standard sheets of ply( 10 foot sheets are available at ?65 each!) so I shortened it a bit,widened it a bit to take two people and re drew things a bit to bring all the elements together.The end result was a quarter scale drawing of what I wanted.There is still a bit of the Javelin in there ,but it is not much. I then joined big bits of card and drew a full size plan. I knew one of my friends had a sheet each of 12mm and 18mm marine ply that he was going to build a Starlet from,but had sidelined the project due to circumstances.It had the main parts marked on the 18mm bit which actually caused me to start following his line with the jigsaw!.I had cut about 1/4 inch before realising!Nobody's perfect!  I ended up swapping an unused 'Midknight' airframe for the two sheets. The ply had been kept in a shed with a broken window,and was a bit discoloured and ragged at the edges, but basically sound.The Project was under way!
 A week or so in the back garden has brought things to the stage you see in the first mock up. I used dowels to show lines,but I still dont know what to use , it has quite tight curves to bend round. I even thought about using dowels laminated and planed down a bit.I still have a bit  to do before I have to decide. Hope you like what I have done so far,it has caused one argument already! Wardrobe building will always come second! Anyway, the project is under way and I even did an artists impression to keep me going and also to decide a colour scheme,usually the most difficult choice. 

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Andy M

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Re: Mini speedboat project
« Reply #1 on: May 03, 2006, 04:58:27 PM »

I was wondering if anyone knew how to work out prop diameter and pitch for  8 HP @ 2500rpm in a 7foot 4inch boat, I want speed! (if possible with only 8 HP!) any help would be appreciated.
Andy M.
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Peter Cobban

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Re: Mini speedboat project
« Reply #2 on: May 28, 2006, 07:54:21 PM »

Excellent Project

I drew out the lines for a Riva type at 10ft long. I was going to power ir with a 15hp outboard which soves propellor selection.

What I would try is to use a 10hp outboard prop, and amchine the propshaft to suit.

Also have a look at "How to design a boat by John Teale. Lots of lovely graphs and other vital information.

Keep us posted on how it all goes, it looks fine so far. In terms of bending, try using two thicknesses of ply, ie 4mm. You will find it easier. If you use quality exterior ply and epoxy resin as a glue you will avoid the expense of marine ply. Pay particular attention to sealing the end grain, and prime wih three or four coats of marine quality varnish.

Best of luck

peter

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Andy M

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Re: Mini speedboat project
« Reply #3 on: May 31, 2006, 11:52:14 PM »

Here are some more up to date photos,it was just slotted together for the first photos,these photos show it glued,sanded and ready to start fitting the skins. Due to my friend being busy at work,I think the hull may be ready before the powerplant.I thought about this when I was designing it and have provision to fit an outboard.If anyone has an 8-10 HP outboard for sale/swap/part exchange,I have a large selection of boats and aircraft for sale/swap/part exchange.I have been offered a seagull outboard of about 2-3 HP which will do for testing,but I had hoped to go a bit fast! It doesn't really have the look I was wanting, either,still,I am sure I will have fun,I have a 3 1/2 year old daughter who asks me daily 'is it finished yet,daddy? If you would like to see some of the models I have , look in 'your models' Andy McGarrity. on mayhem. Keep on building, Andy M.
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Andy M

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Re: Mini speedboat project
« Reply #4 on: May 31, 2006, 11:56:09 PM »

More photos taken after a hard days sanding! Definatey a bit easier sanding a model!l
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Andy M

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Re: Mini speedboat project
« Reply #5 on: June 17, 2006, 01:12:54 PM »

Plenty of progress while weather is good,it's a bit hot at times in my plastic gazebo/shed complex.I have now finished designing and making my steering and throttle arrangements.I bought a seagull outboard from a neighbour,which will be my power unit until we make the outdrive unit for the 8HP honda generator engine.That was the original plan anyway,it was designed for an inboard,to keep it low looking,but I also designed in the ability to use an outboard whenever my friend wanted his generator engine back- he wont sell me it as he is an engine collector! The seagull outboard doesn't actually look too bad.I like the simplicity! Ever tried servicing a modern motorbike? The engine wasn't running when I got it,but about 1/2Hr had it running! Hope you like my project so far.Soon I will be fitting the sideskins which will probably be the hardest clamping job ever! Any suggestions?? Dont say planking!? Have fun, Andy M.           P.s.The centre join on bottom sheeting has still to be sanded to shape!
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Andy M

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Re: Mini speedboat project
« Reply #6 on: June 27, 2006, 11:08:14 PM »

I thought I would add some pictures to show what stage I have got to so far.Weather has been good and I have got quite a bit done,the photos show what I had to do to clamp the side in place. I used two ratchet straps,two lengths of rope,9 large g-clamps,about 12 smaller g-clamps,about 50 bits of wood ,30 metres of bungee cord and,looking at the photo,one of my sanding blocks! It all stayed on until the glue set and I was quite pleased with the join. I hope I can get it as good when I do the other side,I am going to leave that until I have the interior varnished. I have finished varnishing my floor panels and the pulleys for the steering.I was lying inside it today,varnishing,it was a bit cramped towards the bow.I also started my upholstery for the seat,as a change from varnishing. I am making cockpit side cushions/shoulder padding? so I did one of these first, before tackling the main seat. I was impressed with the result,the back of it doesn't look quite as good,but will be hidden anyway. Next instalment soon. I still haven't thought of a name for it,I dont think it looks anything like a Lesro Javelin any more, what do you think?? Can you think of a good name?? ? If anyone wants to aid my varnish fund,you could check out? my models for sale,I have (too) many to choose from,aircraft and boats,boats can be seen on 'your models' - andy mcgarrity .? Hope you fancy something. Keep on building , Andy M.
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Andy M

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Re: Mini speedboat project
« Reply #7 on: July 06, 2006, 05:54:31 PM »

Progress has been good,I now have all the skins on and have started on the spray rails,I had to resort to using softwood,well steamed and screwed to hull on a bead of woodglue and superglued.Probably not conventional boatbuilding technique,but it has worked! I will try to post some photos next time,I still have a lot of varnishing and sanding ahead of me.I am going out now to fit my side spray rail.(dont know correct term) keep on building, Andy M.
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Andy M

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Re: Mini speedboat project
« Reply #8 on: July 23, 2006, 06:38:45 PM »

Here are the latest photos of my progress with the boat.

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Martin [Admin]

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Re: Mini speedboat project
« Reply #9 on: July 23, 2006, 06:46:54 PM »

Looking good Andy.

Martin.
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Peter Cobban

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Re: Mini speedboat project
« Reply #10 on: July 23, 2006, 07:56:27 PM »

What a cracking little boat.
I used softwood for the rubbing strips on the tender that I built for the Yacht. So far, I have no trouble, but I did seal them with resin and the gave them approximately ten coats of paint.

Keep going it looks great.
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Andy M

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Re: Mini speedboat project
« Reply #11 on: July 28, 2006, 10:55:38 AM »

The weather has been very good so I should not have been surprised to see rain when I opened the curtains this morning.Today I am not worried about leaks in my polyhut, my boat is waterproof! I have painters wrist and sanders cramp,so today I am going to have a bit of a rest while I decide what to do next. I was nearly going to change my colour scheme to yellow and white instead of my original idea of yellow and black,but I had the paint sitting there,so black it is. I think the black makes the hull look lower,I might just be imagining it though.This is one of the hardest parts of a project to decide,I did think of having blue on it as well,but financial constraints meant only two colours.These pictures show it with white undercoat on the bottom.

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Andy M

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Re: Mini speedboat project
« Reply #12 on: July 28, 2006, 11:07:12 AM »

Now black on the bottom,still lots to do , but I am getting the urge to head for the water,getting close now. I have a small amount of work to do on my windscreen,which should enhance things a bit,I also have to paint the cockpit edge and the inside of the nose vents.After that, I can re-fit all the other bits. Anyone got a 5-10 HP engine for a test? I am still not that confident that the seagull outboard will be enough,it should still be fun,but the option of speed would be good. Andy M.
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Andy M

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Re: Mini speedboat project
« Reply #13 on: July 28, 2006, 11:22:29 AM »

Here are the photos that were supposed to be with the text!

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Andy M

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Re: Mini speedboat project
« Reply #14 on: August 07, 2006, 04:59:53 PM »

Here are the latest photos, I still have quite a few things to do,but it could go on the water now. I have had an offer of transport to the water next weekend,so I will have to find out about getting it registered for Loch Lomond. Andy M. p.s. Thats not the steering wheel I am going to use!

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Martin [Admin]

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Re: Mini speedboat project
« Reply #15 on: August 07, 2006, 05:48:18 PM »

Fantastic! Show us the mota!  ;)

Martin

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Andy M

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Re: Mini speedboat project
« Reply #16 on: August 07, 2006, 10:01:06 PM »

More photos

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Andy M

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Re: Mini speedboat project
« Reply #17 on: August 07, 2006, 10:03:42 PM »

More photos

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Andy M

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Re: Mini speedboat project
« Reply #18 on: August 07, 2006, 10:18:04 PM »

I forgot which photos were which, so here are some photos of the motor. It is a British seagull forty plus mk2 , 64cc of raw power! It is rated at 1 1/2 -2 1/2 HP. British horsepower,that is, so I don't expect too much in the way of speed,I must find a bigger outboard ,or continue with the outdrive unit and inboard motor. I hope to get out in it soon, so I will post more photos and tell you how it goes. If anyone is interested in making one or a model of one,send a message, 1/4 scale gives a 22 inch long 'easy build' scale model. There are 196 separate pieces of wood in it.       Andy Macyam

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Andy M

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Re: Mini speedboat project
« Reply #19 on: August 08, 2006, 12:58:10 AM »

Just to show how it was started, I have my original Photoshopped picture with my head on a shortened Lesro javelin photo and the final (nearly finished) photo. I will have to get someone to take a photo on the water at the same angle. Andy M.      Go on! Make one.

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HS93 (RIP)

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Re: Mini speedboat project
« Reply #20 on: August 08, 2006, 02:22:03 AM »

I dont like where the propshaft comes out..............Unless its going to be jet drive.....Peter
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Andy M

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Re: Mini speedboat project
« Reply #21 on: August 08, 2006, 03:58:12 PM »

Don't worry, I didn't fancy that either, so I was going to put the engine behind me and run a chain up to top of transom to shaft driving toothed belt onto prop. Toothed belt to run down inside of square section steel drive strut.It is a lot easier to use the outboard,but centre of gravity ends up a lot higher. I need to wait until my friend has spare time at work before I can start on the out drive,it is already designed.The 8 HP generator engine is in my shed, waiting,it even starts first pull!  It will still be fun with the Seagull outboard. Andy M.
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Andy M

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Re: Mini speedboat project
« Reply #22 on: August 11, 2006, 11:07:06 AM »

Had an offer of transport to Loch Lomond yesterday , so I got prepared and by 8pm I was launching my boat. I had phoned about registration and was able to do it at the ranger 's office where I was launching.I was given my set of registration numbers, which,when placed with minimal gaps, are still over 2 feet long, a bit out of scale for the size of boat, motorcyclists usually fit a small plate,so I may be forced to tweak the size a bit.Anyway,back to the fun bit. I got in and tried to start the motor,but was being blown back to shore,so my friend pushed me out again and it started next pull. The waves were no problem,it felt really stable and a bit on the slow side, not a speedboat yet! I had a cruise about and did some turning on the spot,which it is very good at, it turns in it's own length.I came back in and picked up my passenger,which was a bit of a wobbly process until he was seated, enough room  for us and lifejackets! We headed out a bit,round a couple of bouys and cruised about for a while ,before coming back in. The only water in it was from our feet,I am glad to say. The Seagull engine was not as fast as I had hoped ,but will be suitable for taking my daughter out. There are still a few things I can try with the motor to make sure it is running at it's peak performance.(Has anyone run a Seagull on methanol? Will it explode?) Apart from the speed thing,I am pleased with the boat, It looks a lot better than a rowing boat with an outboard,and with a bit more power,I may even get it planing.I need to wait until my wife  gets the photos off her camera,but I will post them as soon as I can. Andy M
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BobF

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Re: Mini speedboat project
« Reply #23 on: August 11, 2006, 01:12:23 PM »

Hi Andy,

The British Seagull engine was designed for torque rather than speed. The entire range of which yours is one from smallest the Forty Minus was the baby, never gave speed, but there was an advert picture they used back in the sixties, with a Seagull Century Plus (or it may have been a 102) fitted to the rudder of a full size barge.

I had a 2hp Johnson fitted to a seven foot mini speed boat which nearly got on the plain.

Bob
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Andy M

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Re: Mini speedboat project
« Reply #24 on: August 14, 2006, 02:11:21 PM »

Here are some photos of the launch.Sorry for poor quality,it was the wife's camera,I will try to get some pictures with my own camera on my next trip,if I can get someone to take me.I really should build a car! Or a trailer for the bike! Andy M.

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