Reliably getting over 70 mph (help please)

Just4Fun · 15-10-2006, 12:15 PM

Although I'm very pleased with my current boat, I miss not breaking through the 70mph barrier that I used to get with my previous boat. (Rinker 236 with 365 Mercruiser)

From looking through the threads there seems no limit to the wealth of advice and knowledge out there and I'd like to tap into it.

Last couple of boats have been inboard powered sportsboats and I want get back to an outboard powered speedboat. Last one I had was a rare Marshan 17, which was a nice size. I don't mind going up a bit in size but don't particularly want to go back over 20 foot for the FUN boat.

Getting the buzz of reliably doing over 70 again (4 up) is critical. I don't need it for skiing or racing.... just bog standard getting the wind through your hair.

One thing that has suprised me is just how much varriation in performance is reported between almost identical rigs with some saying they get 80mph from a rig that others only seem to get 60mph from, and it isn't always clear if difference is down to guts, leg/bullet, jacking plate, ballast, prop, hull material, engine tweaks, tabs, weight distribution, age.... or what !

If there is anyone out there who can confirm their rig is fairly standard but reliably does over 70mph, PLEASE let me know.

If anyone wants to sell such a rig, PLEASE let me know.

Many thanks

Matt · 15-10-2006, 12:21 PM

What's you're current boat & motor combo?

Just4Fun · 15-10-2006, 12:41 PM

SeaRay 310 SunSport and a pair of regular 7.4 mercruisers (2 x 330hp)

Its a good compromise between performance and family boat as it still has galley, loo, berths etc.. Sunseeker style.

Jon Fuller · 15-10-2006, 12:41 PM

Paul Aylett on this forum (ice cream truck) is looking to sell his Phantom 21/225hp 3 litre mariner. boat & motor are lovely, and both 1996, trailer is a bit flakey.

It runs just over 70mph. (genuine)

he's looking for about 10k.

Burty · 15-10-2006, 01:47 PM

A well setup Ring / Phantom 20 /21 needs at least 200hp to just break the 70mph mark and a with a 2.5 260hp you should see the magic 80mph

Taz · 15-10-2006, 06:30 PM

What about 3 260 s?

Matt · 15-10-2006, 07:55 PM

It would sink.

Just4Fun · 15-10-2006, 09:53 PM

I've just been reading on another post that a P21 with 200hp would only achieve 61mph. OK, it seems that it wasn't set up terribly well, but I don't want to be the poor sod who winds up buying something like that thinking it's going to get over 70. I'd be gutted. 69 just ain't good enough....

Am I to understand correctly that the 2.5 efi is a standard Merc product producing 260/280 hp (on model year) and that it isn't an after market modification ? Does it get racing gearbox/bullet as standard ? Is life significantly reduced with these small gearboxes or do they use harder materials to compensate ?

Burty · 15-10-2006, 09:56 PM

merc 2.5 260's were produced from around 1992 to 1998 when it was then replaced with the 280. yes come with bullet boxes and offshore legs. however the price you pay for the power is a rebuild every 100 hours

scottyboy · 15-10-2006, 10:28 PM

100 hours!

Wish my xr2 would last that long without needing a rebuild!

Burty · 15-10-2006, 10:45 PM

Quote:

Originally posted by scottyboy
100 hours! Wish my xr2 would last that long without needing a rebuild!

dude thats only 4.25 days i'm sure it lasts longer than that

Silversurfer · 15-10-2006, 10:49 PM

Quote:

Originally posted by scottyboy
100 hours! Wish my xr2 would last that long without needing a rebuild!

I know XR2s suck! I did 50 hours of boating this summer without an XR2

that would have cost me about 4 powerheads on the old phantom with an XR2!

Just4Fun · 15-10-2006, 10:58 PM

Thanks for the warning. I don't want the cost, hassle and risk of a 100hr rebuild. I'm looking for an outfit that shouldn't need attention during a season. What's next best solution ? Is there a decent recreational motor above 200hp that doesn't weigh a tonne/ton OR, failing that, which 200hp model is reasonably robust with good power to weight ? I've seen a few references to Yamaha 225 but I thought it was relatively heavy. I'm guessing that there isn't as much after market tweakabilty as a Merc too.

As far as arguement between Phantom and Ring, is there really much to choose between them for mere mortals not trying to extract the last 10% ? And as for length, is the benefit of 21 over 20 over 18 (or whatever) primarily in ability to handle a chop or are there other subtle benefits (general balance, stability at speed....) ?

Jon Fuller · 15-10-2006, 11:00 PM

Quote:

Originally posted by Just4Fun
I've just been reading on another post that a P21 with 200hp would only achieve 61mph. OK, it seems that it wasn't set up terribly well, but I don't want to be the poor sod who winds up buying something like that thinking it's going to get over 70. I'd be gutted. 69 just ain't good enough....

Pauls P21 is a very genuine 70+ boat. along with all the niceties of oil injection, engine longevity, and reliability.

All the big power outboard stuff is nice, but it's little more than russian ruelette as to how long ones gonna last.

You can see his boat running in this video (beware, it's about 60 meg, so it'll take a while)

http://media.boatmad.com/gallery/v/m...final.wmv.html

and this one

http://media.boatmad.com/gallery/v/m...rough.wmv.html

and this one

http://media.boatmad.com/videos/truck.wmv

ya cuzuns cuzun · 15-10-2006, 11:15 PM

Mate u need to speak to tony davis on this site he made my extreme do 77 mph totally reliable

Silversurfer · 16-10-2006, 10:00 AM

Quote:

Originally posted by Just4Fun
Thanks for the warning. I don't want the cost, hassle and risk of a 100hr rebuild. I'm looking for an outfit that shouldn't need attention during a season. What's next best solution ? Is there a decent recreational motor above 200hp that doesn't weigh a tonne/ton OR, failing that, which 200hp model is reasonably robust with good power to weight ? I've seen a few references to Yamaha 225 but I thought it was relatively heavy. I'm guessing that there isn't as much after market tweakabilty as a Merc too.

As far as arguement between Phantom and Ring, is there really much to choose between them for mere mortals not trying to extract the last 10% ? And as for length, is the benefit of 21 over 20 over 18 (or whatever) primarily in ability to handle a chop or are there other subtle benefits (general balance, stability at speed....) ?

As far as outboards go Yamaha seem really reliable, when i went to my dealer to get my four stroke serviced and checked over he said he had never seen one go wrong I know they have only made this modle since 2000 but thats pretty cool!

Never had any problems with the Suzuki either Mercury engines have been a pain for me.

Carl · 16-10-2006, 10:06 AM

stuart stuart stuart now come on xr2s are lovely,they just like water to cool them ,not mud,and dont like being over reved when the boat leaves the water ,simple

dont take it to heart im only messing with ya

Silversurfer · 16-10-2006, 10:36 AM

Quote:

Originally posted by carly baby
stuart stuart stuart now come on xr2s are lovely,they just like water to cool them ,not mud,and dont like being over reved when the boat leaves the water ,simple dont take it to heart im only messing with ya

LOL - I know but other engines dont seem to have that problem nothing else has blown up that I drive - Boat wise! And the p16 is out of the water more often than the p20 ever was.

For recreational boating and boating without a full team of mechanics I reckon the engine sucks!

Lars T · 16-10-2006, 01:01 PM

I have my P21 for sale as well.

Boat P21 1998 - perfect condition
Engine Merc 250XS 03 (272HP benched - still warranty until oct 07) 42 hours on the clock
3 props
Detwiler Jackplate
Hydraulic Steering
Momo Steering wheel
2 bucketseats
Rearbench
"sunbed"

"Cuddy" - madress
Cover
New trailer

top +85 gps

Ran 82 yesterday with 3/4 full and 4 people..
Runs flawless 75-78 - after the driver should be fully concentrated..!

looking for something in the 14k region..

Other pics can be sent - have video too..

JamesM · 16-10-2006, 01:10 PM

Quote:

Originally posted by Just4Fun
Am I to understand correctly that the 2.5 efi is a standard Merc product producing 260/280 hp (on model year) and that it isn't an after market modification ? Does it get racing gearbox/bullet as standard ? Is life significantly reduced with these small gearboxes or do they use harder materials to compensate ?

You are correct about the 2.5 efi and yes it does get a racing gearbox as standard. However the Mercury bullet racing gear boxes are not smaller than the standard ones but are alot stronger and so should in theory outlast a standard one if used in the same application.