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Old 06-04-2018, 05:50 AM   #101
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Hey Roflhat, I am new to the forum. I am not sure if i missed it in your posts, I am inquiring about how you were able to switch the tiller handle from push to pull, or did you change something on the carbs? I am hesitant to order the newer style because of it. Any input on that would be great. I have a 91 70 hp 2 stroke, and am in desperate need of improving the tiller handle. Thanks
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Old 06-04-2018, 08:11 AM   #102
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

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Location: Isle of Lewis
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hey, I took it to a local fabricator who flipped on of the gears inside the tiller which changed it over from push to pull. Had to grind back a bit of the other shaft and weld another bit I think.
Discovered earlier this year that there's a guy who makes a kit to convert them, I'll dig out his details for you
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Old 06-04-2018, 05:46 PM   #103
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Yeah if you could that would be awesome, was there one specific model number of tiller handle you were aiming for in particular for that motor? I have the existing friction kit, but i can go any way with that
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Old 06-04-2018, 08:57 PM   #104
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
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This is the place - https://www.facebook.com/traylormccoy/
Not used them myself but been told they make the kits, I imagine they fit most Yam tillers
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Old 24-04-2018, 09:40 PM   #105
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Got some 15mm marine ply to make a new floor for the Zapcat, cut and sanded down, will have four coats of paint too. Does look good having the white and black boats together




Also got the crank for the second engine back, they forgot to weld it so had it welded locally, really nice job


Decided to build another 70hp short shaft, got the leg, transom bracket from a 60hp short and the cowling and pull start from a 60 Enduro. Looking for a 70hp gearbox and powerhead at the moment.


Spent tonight stripping my own engine to change the exhaust, fits well, had to cut 5mm off the tab on the flange. Bought some new carbon reeds from Boyesen to go in as well, hopefully the gearbox is back this week from blueprinting, would be nice to get out in it!
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Old 11-05-2018, 05:51 PM   #106
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
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Sent the gearbox to Geoff at Ocean Racing to be reshimmed with new bearings etc. Got it back last week and got sanding the outisde, took a fair bit of metal from the skeg and a bit from the bullet too, not quite down to the homologation sheet but a lot slimmer than it was. Used filler primer to smooth it off and then 2 thin coats of silver on top.




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Old 13-05-2018, 08:46 AM   #107
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Got out for a blast yesterday, was still quite windy around 20 knots. Engine is running the best it ever has, everything is absolutely spot on. Need to get my steering damper setup though, plenty of speed wobbles now I've removed the bungees. Very very happy with how it ran, got 50 knots with the 15G yamaha, which given the conditions is excellent.
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Old 14-05-2018, 05:04 PM   #108
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Started putting together the steering damper, designed a bracket to mount the tiller to the cylinder. Also bought a bi-directional valve which will hopefully allow me to adjust the stiffness of the steering. Drilled out two of the brass connectors to allow fluid through
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Old 19-05-2018, 09:47 PM   #109
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Country: Scotland
Location: Isle of Lewis
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Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Got the damper setup finished off today, seems to work well but couldn't get out to test it

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Old 23-07-2018, 08:14 AM   #110
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Country: Scotland
Location: Isle of Lewis
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Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Not had perfect weather for testing recently but got a couple things done, re-bled the steering damper which is much for effective now. Bought 1m length of ali angle which I'm going to fit across the transom to strengthen it, credit to fel2 for the idea. Had some really bad weather last week so decided to go out anyway, excellent fun. Managed to break the throttle roller, I've now had another waterjet out of aluminium, pretty sure this one won't break!
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Old 30-07-2018, 08:26 AM   #111
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Got the new throttle roller fitted, along with the 1m length of ali angle along the transom. Definitely an improvement, boat feels far more drivable in choppy conditions, especially with the steering damper too.


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Old 19-08-2018, 04:33 PM   #112
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Got my other 70hp project up for sale - https://www.ebay.co.uk/itm/113201949134?
great start if somebody wants to build the ultimate thundercat engine
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Old 27-09-2018, 04:30 PM   #113
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Had some cracking days out through the summer, got out for a run a while back 3up in mine and 3up in jacks, went into some of the caves and arches around Uig.

New drybag, all black of course


Weighed the boat and engine, with around 10l of fuel and the anchor, came in at 171.5kg. Just doing final preparations for Coniston next month.

Got a new helmet for it, courtesy of Douglas Curley at Eric Young & Co. who are very kindly sponsoring me.

Bought a dial indicator and used an old record with a degree wheel sticker to do the timing. Never managed to find a service manual for this engine but spoken to lots of folk, mine was at 21 degrees at WOT, now adjusted to 23 so will see how it goes. Been told I can go higher but dont want to go blowing holes in the pistons


Photo from last year
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Old 27-09-2018, 04:35 PM   #114
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Some exciting development on the props I designed too, making decent progress with them. Should be ready for testing soon hopefully



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Old 09-10-2018, 12:33 PM   #115
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Country: Scotland
Location: Isle of Lewis
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Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Getting a lot of testing done just now, different engine heights, propellers etc.
Got the first 2 Forge V1 cleavers back, one tuned to design spec the other tuned up to 19p and more lift. So happy with them, they run superbly and really fast. Awesome acceleration and still better top speed than the Mercury equivelents. Absolutely delighted with them. Having another 2 set up just now, one with less diameter and one with a "stealth" cut on the leading edge.



New helmet is super comfy too, think I'll start wearing this more often on the boat


A bit of weight reduction too, cut the steering bracket (only used on circuit class boats). Means I can trim the engine further in and also it weighed 1.8kg.
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Old 04-11-2018, 12:42 AM   #116
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Successful time down at Coniston Powerboat Records Week. I’ve been out every day except Wednesday, which I spent re-tuning the engine to squeeze a bit more out of it. On Monday I got 62.79 miles per hour, 63.65mph on Tuesday, 67.83 on Thursday and after three runs this morning I hit 69.99mph twice, and then reached 70.10mph, faster than the existing world record of 67.47mph. Hit 74.9mph on one run today!

Huge thanks to my sponsors -
Douglas Curley at EYCO
Mathesons Furnishings
Gulfxstream Limited
Seatrek Marine Commercial Boat hire
Specialist Small Craft Ltd - Marine Distribution
Lochs Diving Services Ltd
Venture West
Fraser Ralley
Islay Seafari

Thanks to Adrian Morse for the use of his propellers too


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Old 11-11-2018, 05:29 AM   #117
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Boat make: P18,Focker(this focker wasnt a Messerschmitt) 215, Concord, Bristol
Engines: Suzuki DF 140, Yamaha 130 race, Mariner 135
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Awesome work��
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Old 18-11-2018, 01:23 PM   #118
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Country: Scotland
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Boat make: Thundercat
Engines: Yamaha 70ces

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Quote:
Originally Posted by mdm1uk View Post
Awesome work��
Thanks!

I've sent the powerhead away for more work, will still be standard but to homologation spec, essentially blueprinted. Got a few more things I'm going to try, fancy gearbox oil, a bit of weight reduction although I think I'll be lucky to get 2kg off. Don't think I can go for my carbon fibre cowling idea within the rules.
Got some other ideas too, even considering replacing a lot of stainless bolts with aluminium. Ceasar do make a faster hull which is around 4kg lighter too, that would be the biggest step but looking at around £3k for that.
Getting a new billet exhaust made, just to design spec.

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Old 19-11-2018, 07:30 PM   #119
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Country: Scotland
Location: Isle of Lewis
Occupation: Skipper
Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Think I'll go ahead with a new boat, a Macleod Special for high speed, won't be quite as good in the rough though.
If anyone is interested in buying the F10 hull let me know, I'd be looking for around £2400

Exhaust is now finished, looks really good

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Old 18-12-2018, 10:08 PM   #120
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Country: Scotland
Location: Isle of Lewis
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Boat make: Thundercat
Engines: Yamaha 70ces

Join Date: Apr 2014
Location: Isle of Lewis
Posts: 554
Lots of plans for over the winter, mostly small fairly boring jobs. Doing all the weight reduction I'm allowed to, even if it's just grams.



New exhaust is fitted, I took the tiller apart and removed all excess wiring.
Also sharpened up the trailing edge of the gearbox, the idea to join up the water more smoothly and reduce drag. It will be getting painted again along with a few other bits. Thinking of bead blasting the block, looks cool and also saves weight on paint.

Had my 15G Yamaha bored out at the gearbox side and then spent about half a year with the dremel smoothing it out. Will get it balanced before I use it again.

Got a new block courtesy of Davie Anderson, free of charge can't thank him enough. Bottle of whisky is on it's way to him


Also going to try and use a smaller steering damper setup. Shame as mine is working absolutely perfectly but it weighs about 3kg. Normally no problem but I'm trying to save all the weight I can. Will probably have to use heavier oil to get the stiffness required, and may have to get it revalved.


Tried to work out an equation for propeller pitch optimization, pretty basic stuff and I'm not going to work from it but doesnt' actually look too far off. Not using my absolute max speeds as I only tried 1 propeller at those settings.


Thinking of finding the best height for the engine on the new boat and then removing the jacking plate too, to save weight. Even going to remove the visor cap from my new helmet to make it more streamlined.
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