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Author Topic: Mini speedboat project  (Read 17440 times)

tigertiger

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Re: Mini speedboat project
« Reply #50 on: May 13, 2007, 01:38:21 AM »

Congrats
and you deserve to be happy and proud

look forward to some pics
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Andy M

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Re: Mini speedboat project
« Reply #51 on: May 13, 2007, 02:19:56 AM »

Here you are then, I still have to get more photos and video from some of the people who attended the launch. The on water pics are not as good as I hoped, a bit far away. The water was shallow till quite far out and no-one fancied paddling out for a closer photo. Once my Mum has read the insruction manual for her super camera, I might get a picture of it planing. There was mention of going out tomorrow, that's what happens if you give people a shot. My engineer friend was talking about doing a boat (150% stretched Viper,about 11 ft long maybe a bit wider) for himself now using an XS 250 Yamaha bike engine with a prop shaft and rudder etc. We found out that weight needs to go forward anyway, this would allow seats to be moved back a bit and give more open cockpit. But that's another project.  Gears on a boat? does that work?  I promise more pictures soon, next time out it might be sunny! I want someone to wade out waist deep till I do a flypast for the camera but dont think anyone is going to volunteer for that. Andy M
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tigertiger

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Re: Mini speedboat project
« Reply #52 on: May 13, 2007, 03:09:35 AM »

I love the wheelie  ;D  ;D  ;D

She looks good.
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Daniel

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Re: Mini speedboat project
« Reply #53 on: May 13, 2007, 08:03:59 PM »

Hi Andy M,
a good looking boat there  ;D
Hope all goes well with gettin' those pics and the boat runs as good as it looks.

thanks
Daniel
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omra85

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Re: Mini speedboat project
« Reply #54 on: May 13, 2007, 09:42:49 PM »

Well done Andy - you nutter ;D
The prop is a LONG way under the hull so will try to act like a lever on the back - hence the wheely!
Could you raise the engine (maybe by clamping a riser on the transom) to get the prop higher?  I know the engine was cheap and rebuilt by yourself (again, having seen how it started, well done) but you really need the prop JUST below the hull.
Either that or a good lifejacket and a breeze block in the nose ;D ;D
Danny
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Andy M

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Re: Mini speedboat project
« Reply #55 on: May 15, 2007, 12:21:33 PM »

Here is a photo of it on the plane with the two drums of cable up front, I will be trying to put some lead up front permanently. I just wish I had known about that when the frame was still unskinned. Don,t know when I will get out next, can't wait now that I know it's quick ! Have fun Andy M.
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Daniel

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Re: Mini speedboat project
« Reply #56 on: May 15, 2007, 05:31:21 PM »

Hi Andy M,
How fast do you think you got it then?
Looking at the photo it must be seriously quick, Just wish I could one!!!!!  8)


Thanks
Daniel
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Andy M

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Re: Mini speedboat project
« Reply #57 on: May 19, 2007, 01:07:50 PM »

Hi Daniel,  the guy that owns the boatyard in Balmaha thought it was doing 20-25 knots. I have been at 30 knots in a Microplus( as far as I can remember) with 80 hp  motor and it didn't feel as fast because we were standing up. With the Viper,you are sitting at waterlevel. I was hoping to get out today,but it's a bit rough, probably be like The Perfect Storm in my tiny boat. I have to content myself with watching the video (over and over). I had a bit of an 'Incident' when I was casting lead to fit up the front of my boat, I had cast the bit I needed and was pouring the extra lead into an ingot mould when an explosion of molten lead spurted up from the mould and splashed on my arm! Pretty sore! So I decided to ladle the rest into the mould instead of pouring it,thinking that would be a bit safer! How wrong can you be, as soon as the ladle touched the molten lead, it really exploded this time ,sending a shower of molten lead in an 8 ft radius circle, with quite a bit of it landing on my neck and running down my shoulder! Now that REALLY hurts! It wrote off a pair of trainers,a pair of trousers and a t-shirt. I managed to finish fitting my ballast the next day so it's not that bad,but I had 3 splashes on my glasses,that was the most worrying thing. I will have to change my 'motto' from Have fun to Have fun and be careful with lead, Andy M
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Andy M

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Re: Mini speedboat project
« Reply #58 on: May 19, 2007, 01:17:07 PM »

I am thinking about making a fibreglass moulding of it, I ordered a catalogue to see how much it would cost to start producing them,but I have no experience with fibreglass. I don't know the best way to make the mould,or if it would come out, I would probably have to remove the side rails. Is there anyone that would want to buy one,I am sure a fibreglass one would be a lot lighter/faster. 
Anybody out there live near Balfron and knows about fibreglass? Andy M
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Andy M

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Re: Mini speedboat project
« Reply #59 on: May 19, 2007, 02:14:25 PM »

Well, here is what molten lead does to skin. Don't  try this at home! (always wanted to say that) It's started to go crispy! Have fun, Andy M.
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Andy M

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Re: Mini speedboat project
« Reply #60 on: May 19, 2007, 02:53:21 PM »

Here is my onboard video (if it works!)http://www.youtube.com/watch?v=-YKATWyFMYE
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omra85

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Re: Mini speedboat project
« Reply #61 on: May 19, 2007, 04:05:02 PM »

No Andy - no video there (at the moment)  Here's the link
www.youtube.com/watch?v=P3OfHl2dDo8

Danny
Thats a horrible photo - the injury looks bad as well  ;D ;D

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John W E

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Re: Mini speedboat project
« Reply #62 on: May 19, 2007, 06:22:19 PM »

Hi Andy, I know its a bit late now, but did you consider using a barrel filled with water placed in the bow?

The alternative, if not a barrel filled with water, did you think about putting trim tabs on the bottom of the boat, that is another option.

Another option I can think of is, if you can slightly angle your outboard motor, so that the prop actually faces down over so the thrust of the prop is actually pushing the stern of the boat up over and the bow down over.

No doubt you have worked it out for yourself, but, you have miscalculated your centre of gravity for forward motion thrust  ;D  - a very quick and simply description - imagine a see saw - the bench that you actually sit on represents the boat, the centre piece which holds the bench up is the centre of forces acting up over from the water.  As the boat moves forwards on a normal displacement hull, this centre moves slightly aft, different (now we are considering Andy's boat - a high speed boat) as the boat increases speed it comes to a state which is known as the hump, where the boat is now at a speed where it is attempting to climb over the top of the bow wave.  This bow wave is now your pivotal point.   If you have too much weight in the back end of your boat, you have what has happened to Andy's boat - the bow just lifts straight up in the air.

To compensate this, there are several ways, one which Andy has done - that is to add weight to the bow - then obviously the other way is a more complicated way which entails re-designing the hull. 

I have a sneeky feeling Andy is going to go for a 3-point hydro next.

WELL DONE ANDY ON YOUR BOAT  ;D  Make the next one slightly longer.   Make sure you can sit further forward towards the bow.

aye
john e
bluebird
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Andy M

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Re: Mini speedboat project
« Reply #63 on: May 19, 2007, 09:03:47 PM »

I must say that the boat is pretty heavily built,look at the bare frame further back in this, 3 layers 3/4 ply for keel, same for engine mount(as it was originally for inboard or outboard) and 2 inch thick transom. most of the bulkheads have partial doublers resulting in a 15 stone boat! Plus my 2 1/2 stone of lead now! A 5 stone engine hanging over the back as well. When I tried to get it on the plane with two people aboard,but without cable as ballast, it seemed as if it was the same as with one person, we never had time to try 2 people and ballast, I will the next time. Anyone got an estimate of how heavy a fibreglass hull would be compared to my wooden version, anyone got a 15hp they would swap for some of my vast model collection? Volvo penta outdrive? I even thought about grafting a Suzuki 250 Gamma engine onto it,but didn't think my gearcase would take the power,Captain(in a real Scots accent!)I think it's actually fast enough ,but the biker in me takes over and I want more speed,who mentioned hydro? One of my first models was a Robbe Proppy,has anybody got a picture of one, I remember it being pretty fast with a standard buggy motor,in fact, everything out of my Tamiya Holiday buggy. I would like a photo if anyone has one. I priced a speedo for my boat and it's 3/4 what it cost to build the motor,and besides,I was told it looked about 20-25 knots(by someone who works with boats) thats good enough for me, it feels fast, I don't want to find out it's only doing 13 knots or something. Doesn't matter,feels like you're going for the water speed record! It was pretty calm when I was out,I am sure the excitement level will rise with the size of the waves.It's a deep v hull so should be able to handle it(he says hopefully). The side of the boat at the Viper logo is 12 inches high! I have seen five foot waves on Loch Lomond,thats 2/3rds the length of my boat. I know I am going to have fun in it,anybody fancy making one ? It's just a big model and if you take the motor off,it can sit on it's transom in the corner with the telly in the cockpit. I have had a lot of fun designing and building it,it took a while,but I ironed out the problems and ended up with somehting that goes as fast as I had hoped,Andy M
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John W E

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Re: Mini speedboat project
« Reply #64 on: May 19, 2007, 09:35:54 PM »

Andy, in a real Geordie accent  ;D go for the 3 point hydro next time - about 15 foot long and stick a 25 horse Yamaha on the back end - with you sitting well foreward -  ;D

On the serious side though, if you are ever planning to do something like this again, which no doubt you are, if you can get hold of a book entitled 'High Speed Small Craft' by Peter Du Cane 3rd updated edition.  Its heavy reading, but its got a lot of formula for predicting required horse power per weight of boat to get a set speed.

To give you an idea - 39 foot boat weighing 7 ton - took 2 x Ford V6 engines - driving 13" pitch by 14/15" props.  This gives a speed of approximately 22-23 knots.   That was on a similar hull as what the perkasa is.

Its worth looking into anyway and it gives you a ball park figure to aim for, for sizing your motor.

aye
john e
bluebird
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martno1fan

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Re: Mini speedboat project
« Reply #65 on: May 20, 2007, 12:14:52 AM »

hi andy have a look at some of these all the plans are free and there are some that might be of interest,should keep you busy for a few years at least lol  ;D
http://www.svensons.com/boat/?p=HydroPlanes/minimost
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Andy M

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Re: Mini speedboat project
« Reply #66 on: May 20, 2007, 01:00:08 AM »

I dont really fancy sitting on a modified ironing board,Andy M
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martno1fan

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Re: Mini speedboat project
« Reply #67 on: May 20, 2007, 07:32:19 PM »

I dont really fancy sitting on a modified ironing board,Andy M
i must have missed the ironing board these boats are tried and tested ,some even raced and still do in the states  ??? ::) :-\
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Andy M

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Re: Mini speedboat project
« Reply #68 on: June 15, 2007, 02:00:10 PM »

Here is the new link to the onboard video  http://www.youtube.com/watch?v=-YKATWyFMYE
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Andy M

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Re: Mini speedboat project
« Reply #69 on: June 15, 2007, 02:06:24 PM »

Anybody got a speed estimate? Have you ever wished you hadn't got yourself in a video?
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martno1fan

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Re: Mini speedboat project
« Reply #70 on: June 15, 2007, 05:36:53 PM »

seems like shes going pretty well mate id say speeds about 25 mph !!be nice to see a video of the actual boat running to see how shes riding now?.
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Andy M

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Re: Mini speedboat project
« Reply #71 on: June 16, 2007, 12:07:24 PM »

 Your wish etc.Here is video of it planing.Sorry about the quality, I had to use my phone to record it off the telly, I will try to put the original digital footage on,but my Mum has it and it needs editing. http://www.youtube.com/watch?v=aAoei2F87Gs
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martno1fan

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Re: Mini speedboat project
« Reply #72 on: June 16, 2007, 06:39:59 PM »

nice video mate she looks great certainly seems to be planing  ;).
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Andy M

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Re: Mini speedboat project
« Reply #73 on: June 26, 2007, 11:47:31 PM »

Hi everyone,I managed to get out again on Sunday,it was very wet but I decided to risk getting my leather upholstery soaked and have another shot. Since I was there last,the speed restrictions have changed on Loch Lomond,with many areas being 11kph. The place I launch from has this limit extending 1/2 mile offshore where before,it was 150mts. My friend had a shot and was a small yellow dot before he opened it up a bit,I couldn't even see if he was planing or not! So much for getting some close up video or photos. I took a few of it before we loaded up. The lead does the trick,but I found that by sliding forward again once you are planing,it goes a bit faster.This would suggest that it could do with a bit more. It was pretty choppy out at the half mile markers,I was looking for some larger waves to see how it would cope,then a jetski went past about 100yds away and I headed for a 'clump' of waves that seemed to be gathered in one place,it looked a bit odd but I drove? through it and I thought I got airborne but dont know for sure,it felt like it was landing,it was quite a thump. I got pretty soaked from rain and the half bucketfuls of water from the bow area that seemed to happen often. It felt as if I was crossing the Atlantic even though the waves were only about a foot high. Hope it is a bit sunnier and drier for my next outing. Have fun , Andy M
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Andy M

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Re: Mini speedboat project
« Reply #74 on: July 18, 2007, 12:36:58 AM »

I managed to get out again on Sunday,it wasn't even raining! I will be putting some videos on youtube sometime soon, I need to stop getting myself in the videos, Andy.  http://www.youtube.com/Macyam
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