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07-05-2005, 01:16 PM
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#1
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Registered User
Country: England
Location: Birmingham
Occupation: Scratching
Interests: Big Dinners
Boat name: Never Enough
Boat make: Seaquel 600xs
Engines: 225hp Merc ProMax
Cruising area: Anywhere! I prefer Weymouth
Join Date: May 2005
Location: Birmingham
Posts: 3,232
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Inboard engines
As I want to go faster in my Marshan I have been thinking of ways to do it!
So I was thinking of using 1000cc Motorbike engines.
You can pick up fireblade engines cheaply enough these days that have a bhp of 150hp with a max rpm of about 11000rpm-13500rpm.
I think you would be looking at about 90-95mph on a 21p prop.
As these engines are small and light weight it should be a snap to install one into the back of a boat.
WHAT YOU ALL THINK???? AM I DREAMING??? OR JUST PLAIN OLD MAD????
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07-05-2005, 01:18 PM
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#2
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Registered User
Country: England
Location: Birmingham
Occupation: Scratching
Interests: Big Dinners
Boat name: Never Enough
Boat make: Seaquel 600xs
Engines: 225hp Merc ProMax
Cruising area: Anywhere! I prefer Weymouth
Join Date: May 2005
Location: Birmingham
Posts: 3,232
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at 10000rpm, 1.63 gear ratio, 21p prop, and 15% slip that would + 104mph!
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I got jumper cables!
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07-05-2005, 01:45 PM
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#3
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Registered User
Location: Essex
Boat make: Phantom 21
Engines: Merc 2.5efi
Join Date: Mar 2005
Location: Essex
Posts: 337
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Keep takin the pills!
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07-05-2005, 06:27 PM
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#4
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Registered User
Country: New Zealand
Location: Auckland
Occupation: Construction Manager
Interests: Offshore Powerboat Racing
Boat name: NZ Privateer
Boat make: 29ft Catamaran
Engines: 2 x Mercury 300X
Join Date: Dec 2004
Location: Auckland
Posts: 214
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how do you propose to get the power into the water?
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07-05-2005, 06:51 PM
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#5
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Traveling
Country: UK
Location: Alderholt
Occupation: Aerospace
Boat name: T/T D2S
Boat make: Midas 27' Cat, Argo 16 Cat. Avon Rib Thingy
Engines: Merc 280-ROS -JSRE,65Xs, 75 Stinger, Yam 60
Cruising area: Any Seedy Bar
Join Date: Sep 2004
Location: Alderholt
Posts: 4,225
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Been there tried it, with 2* 500 yam GP two stroke motors, gearbox was a nightmare & would run out more expensive than buying two bran new XR2's when they first came out.
Yam put them up for the old boy to try when they raced with them.
power was great but hooking it Up was just not cost effective
But it was a Copland, Buzzi, Idea, tune the feck out of it coz it's now an inboard under the regs of the day.
Now putting the block on an outboard leg that could work if it's just for fun.
£££££££££££££££££££££££££££££
my thoughts "Spend ya time on the water, not in the garage"
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07-05-2005, 08:42 PM
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#6
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Registered User
Country: England
Location: Great Horwood
Join Date: Mar 2005
Location: Great Horwood
Posts: 2,372
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Or how about constructing an aerodynamic wing over the boat? A few race boats tried this with good results (Buzi, Cougar amongst them) until they were banned for racing. The bat boat wings clearly generate lift and add to speed.
Could be a fun and far cheaper way of going quicker, plus it will create a bit of interest on the slipway!!
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07-05-2005, 11:13 PM
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#7
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Registered User
Country: England
Location: Great Horwood
Join Date: Mar 2005
Location: Great Horwood
Posts: 2,372
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this idea..
you can make the wing trimable with hydraulic rams -
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07-05-2005, 11:26 PM
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#8
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Registered User
Country: England
Location: Great Horwood
Join Date: Mar 2005
Location: Great Horwood
Posts: 2,372
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The other thing you could try is Ocke mannerfelt Speed Rail TM
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08-05-2005, 08:22 AM
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#9
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Registered User
Join Date: Apr 2004
Posts: 184
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Wouldn't the speed rail cause more 'slam'?
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08-05-2005, 08:26 AM
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#10
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Registered User
Join Date: Apr 2004
Posts: 184
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Erm.. before I got distracted, another issue I see with 4 stroke bike engines is the entire lack of bottom end grunt. Running just a single speed gearbox will see you struggling to get through the lower rev range before any useable power comes in.
In my humble opinion of course.
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08-05-2005, 09:10 AM
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#11
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Registered User
Country: England
Location: Birmingham
Occupation: Scratching
Interests: Big Dinners
Boat name: Never Enough
Boat make: Seaquel 600xs
Engines: 225hp Merc ProMax
Cruising area: Anywhere! I prefer Weymouth
Join Date: May 2005
Location: Birmingham
Posts: 3,232
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I think that problem could be over come with using a lower ratio gear box and tuning the engine. After talking to my mate who is bike nuts yesterday the said you could easily tune a honda CBR engine upto 220bhp easy and have a red line of about 15000 - 16000rpm. Put that on a 2.1 ratio back and with that rav range your talking some serious high speed!
BluFin had an interesting idea of wacking the engine onto an outboard leg. I have a friend of a friend who makes adaptor plates to fix modern gear boxes to big old V8 for the kit car industry, I'll see what he thinks!
Rob.
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08-05-2005, 11:53 AM
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#12
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hello
Join Date: Mar 2004
Posts: 2,739
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I would have thought that if you tune a 1000cc bike engine upto that sort of power it would all be in a very narrow rev band right at the top of the range. That would be even worse than the standard motor. Boats need motors with lots of torque and wide power bands as they only have one gear that has to take it from a standstill to flat out.
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08-05-2005, 11:54 AM
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#13
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hello
Join Date: Mar 2004
Posts: 2,739
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It might work on a very light weight hull.
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08-05-2005, 12:26 PM
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#14
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Registered User
Join Date: Apr 2004
Posts: 184
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Quote:
Originally posted by MrRob
I think that problem could be over come with using a lower ratio gear box and tuning the engine. After talking to my mate who is bike nuts yesterday the said you could easily tune a honda CBR engine upto 220bhp easy and have a red line of about 15000 - 16000rpm. Put that on a 2.1 ratio back and with that rav range your talking some serious high speed!
BluFin had an interesting idea of wacking the engine onto an outboard leg. I have a friend of a friend who makes adaptor plates to fix modern gear boxes to big old V8 for the kit car industry, I'll see what he thinks!
Rob.
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I must agree IMO with Johnny Boat Dude. It's not the out and out power that makes a fast useable boat it's a continuous power/torque throughout the rev range. Remember most marinised car engines are de-tuned to provide a more even spread of power.
Imagine riding a bike everywhere in 4th or 5th gear.
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08-05-2005, 02:33 PM
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#15
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Registered User
Country: UK
Location: Swansea
Occupation: Computer Director
Interests: Anything with an engine
Boat name: Too Blue
Boat make: RIB 9m
Engines: Suzuki 225efi
Cruising area: Bristol Channel/Irish Sea
Join Date: May 2005
Location: Swansea
Posts: 101
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Quote:
Originally posted by darexms
I must agree IMO with Johnny Boat Dude. It's not the out and out power that makes a fast useable boat it's a continuous power/torque throughout the rev range. Remember most marinised car engines are de-tuned to provide a more even spread of power.
Imagine riding a bike everywhere in 4th or 5th gear.
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Couldn't agree more - a steam traction engine may only be 8 or 12hp but pulling power - will easily outdrag a modern tractor puller/racer with 1500hp!!!
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08-05-2005, 06:10 PM
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#16
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Registered User
Country: New Zealand
Location: Auckland
Occupation: Construction Manager
Interests: Offshore Powerboat Racing
Boat name: NZ Privateer
Boat make: 29ft Catamaran
Engines: 2 x Mercury 300X
Join Date: Dec 2004
Location: Auckland
Posts: 214
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why dont you just go and buy a 2.5EFI Offshore, it will probably be cheaper in the long run, Mercury have already spent the dollars in R and D.
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