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Old 18-08-2005, 11:08 AM   #1
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Need To Re-Engine My Tomahawk

I purchased a 89 Sunseeker Tomahawk this year in the knowledge that the engines were knackered(they got wet and siezed some 3 yrs ago, and were restarted). Well I have discovered that they were even more knackered than I though and hoped to run them for the rest of this season. Whilst I love the 454 Petrols, diesel has to be the way on a 5.5 ton Shed. I basically bough the boat without engines anyway and I am having a sad retro Miami Vice faze.....

I am looking at doing something like Merc 300 Diesels with Bravo 3 legs.

Firstly any other suggestions ?
Secondly would like to keep the cost under £20k.
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Old 18-08-2005, 02:33 PM   #2
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under 20k - gotta be 2nd hand eh

Are the old legs knackered too?
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Old 18-08-2005, 02:50 PM   #3
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The legs are new Bravo One's they have only been in the water about 2 months in total. They were replaced by the last owner who went about fixing everything but the engine.
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Old 18-08-2005, 03:06 PM   #4
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Ok - so the 20k is just for engines?
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Old 18-08-2005, 03:18 PM   #5
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That's a sign of the times. A bloke in the channel isles complaining about the cost of running petrols!!
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Old 18-08-2005, 03:24 PM   #6
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Its gotta be bout 50p per litre on Guernsey now??
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Old 18-08-2005, 05:04 PM   #7
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I would love to go an buy some crazy big block Petrols to replace them, as the noise, smell etc is just awsome.....

But there is no market for big petrol boats, so my sensible head says diesel, plus the fuel distance thing is massive.

Just working it out that the diesels are 4.1 ltr and produces 300 hp and 1 litre of diesel produces 20 hp. Times by 2 against

Petrols 7.4 litre producing 365 HP and 1 ltr of petrol produces 12 hp. Times that by 2.

By the way Petrol here is 58p, massive and shocking I know, what is the world comming too.
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Old 18-08-2005, 05:21 PM   #8
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1 litre of diesel will produce as much power as you want - over what time period is the important detail that makes the difference.
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Old 18-08-2005, 05:27 PM   #9
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K'in ell!

Last time (<1 yr) I was home in Sark it was 45p - has Mr.Brown been on holiday to the Islands recently!?!

If you can find ones for the right price then for years I've heard nothing but good things about Yanmar 6LPA-STP (315 hp)
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Old 18-08-2005, 06:28 PM   #10
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They need the extra tax income to fund all the drying out clinics over there, its not easy having a population of 80,000 when 79,999 are in re-hab.
Morgs moved to the Island when Oliver Reid died - they needed a replacement!
He navigated for me in 3C in 1988 in the Euro Champs over there, took his chart, compass and 6 cans of Grolsch with him!
Dreadful place.

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Old 18-08-2005, 06:34 PM   #11
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Quote:
Originally posted by John G
I've heard nothing but good things about Yanmar 6LPA-STP (315 hp)
You need to get your ears syringed then!

As good as they are, they do suffer from terrible turbo lag, are incredibly dirty engines and have problems with breaking blocks and drives!

Your chances of finding some s/h ones are very slim, unless you don't mind buying knackered! Mind you i did buy a s/h package from Barrus last year and it's turned out to be ok so far!

As your replacing b/b Chevy’s, it would be worth considering the AM General (GM) V8 6.5l motors as fitted to Jon's Phantom, they are a direct replacement for the b/b, (same footprint and bolt pattern) and seem to be kind to Bravo's. You could even salvage the ancillaries from your old motors, including flywheel covers, drive plates etc!
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Old 18-08-2005, 07:21 PM   #12
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must've been listening to the RIB guys too much!

Know they're mounts break but reckon that's more to do with the stringers beneath flexin too much. How come they break drives - too much torque? If so its hardly the engine's fault! Good to hear another side of the story though - in the commercial market they're no.1 choice for most. Power to weight is good and thought they were v.reliable.

Sounds like for the Tomohawk the GM's could be a great idea especially given the 20k budget. How do you rate them TD - good for the long run? or should Jon be answering this?
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Old 18-08-2005, 07:35 PM   #13
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Have you thought about a couple of 225 Opti's on the back?

I have thought the tomahawk is a sexy boat for years, always wanted one but never enough cash to date.

I thought maybe with a couple of opti's I could save a lot of fuel, weight & space. I realise the bathing platform would be largely lost but:

For shallow waters such as Poole Harbour I could trim out & access places a boat of this size would not normally reach.

Stick my Dingy or Kid in the redundant engine bay.

Save loads on fuel compared with the inboard petrols. I also think Diesel will be taxed in the not too distant future so running costs should still be cheaper if this happens.

Also think speed would not suffer.

Just my thoughts on the subject any feedback would be nice as I still plan to go this route.

Cheers
Kev.
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Old 18-08-2005, 07:39 PM   #14
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Have you thought about a couple of 225 Opti's on the back?

Cheers
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Old 18-08-2005, 07:48 PM   #15
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I've heard it all now!

I take it you don't like this idear then. Any chance of some constructive comment as I'm not a boat builder & could do with some advice.
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Old 18-08-2005, 10:16 PM   #16
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No, not at all. I like it when someone does a bit of thinking "out of the box" so to speak. I'd be happy to air saw the bathing platform off for you, then you'll just need a huge structual repair, either retro an engine well or install a "gil" type bracket and fit a couple of Opti's. Probably need to enlarge the fuel tanks for a decent cruising range, and leave a day earlier to get there, but should work fine!

Might not do a lot for the resale value, but cost obviously doesnt come into it so why should you care!!!
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Old 18-08-2005, 10:33 PM   #17
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feck me......who's got his sarky cap on then?
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Old 18-08-2005, 10:36 PM   #18
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That was my second boat! It had volvo penta petrols in it.

I wanted to replace them with diesel, but there were too many issues, so I bought a boat with diesels already fitted...

I think diesels cost more initially, but are cheaper to run. You gotta think how many hours of use you get out of the boat to justify the cost of the diesel engines.

Petrols are cheaper, and you can use the money saved to fund the additional cost of petrol....
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Old 18-08-2005, 10:37 PM   #19
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feck me......who's got his sarky cap on then?
Eh, what, me??? No, I like the idea, after all I've seen photos of Compton Ribs with 8 yammies on the back so it's all quite possible!

And anyway, it'd probably only be a little heavier than a certain P21!
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Old 18-08-2005, 10:42 PM   #20
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I Dont want to talk about 'him'!
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