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Author Topic:   MISCHIEF 15: Re-power Above Maximum Rated

oceanloverny posted 02-24-2005 10:35 AM ET (US)
My 1988 Mischief 15 is currently powered by a 70-HP outboard. Based on calculations from "whaler reference" [?] the result is 83-HP. Rounding up by 5-ish would give 90-HP.
Am I making a big mistake by putting a 1988 115-HP? that I have on it. Has anyone first hand experience with a 115-HP on [this] hull?
Thank you.
skiff posted 02-24-2005 11:15 AM ET (US)
Whoa, a 115? I have a Mischief with a 70-HP Yamaha, and it has plenty of push. I'm sure you've checked the extra weight, but I'd think that the transom might sit a bit too low with that size rig on the stern. I use my boat on the ocean primarily, but on a lake, where I can finally get her up to top speed with the 70-HP, I detect a bit of chine walk--God's way of telling me to slow down. With a 115, I'd think you'd get going faster than that hull should mathmatically be driven.
dscew posted 02-24-2005 11:16 AM ET (US)
I think the result would be a stern heavy missile, and I would [not] want to be on the water when it was at full throttle. Way overpowered, IMHO.
jeffs22outrage posted 02-24-2005 11:42 AM ET (US)
When I was growing up, we had a 75-HP Mercury--5-HP above recommended--on our 15 SUPE SPORT. It would hit 60-MPH with ease with one person in it, a friend in the marina called it the ICBM (intercontinental ballistic missile). I scared myself a couple times at WOT getting a gust of wind under the bow, boat would lift and chine walk like crazy. At WOT the hull was almost completely out of the water. The boat with one person and a full tank of gas had just inches of freeboard, I think the 115-HP will sink the transom. My father has 90-HP on his MONTAUK and it will do 50-MPH or more, and that boat is longer and heavier than the 15-foot. Over powering a little whaler is more likely to get out of hand than over powering a boat like an Outrage.
BOB KEMMLER JR posted 02-24-2005 12:26 PM ET (US)
Oceanlover--What make of 115 were you thinking of using? The older 6-cylinder Mercury motors were only 295-lbs., so the weight shouldn't be that much of a factor. The mischief is a little heavier as well, so it should take a little more horsepower to get the same top speed as a standard with a 70 on it. I say put a 6-inch jackplate on the back, get hydraulic steering, low water pickup nose cone, surface running prop, hot foot throttle, foot T&T unit, helmet, life insurance. and pick a dead flat day on the sound. You can also offset some of the transom weight by running a larger fuel tank under the front deck and placing the battery up front. I wonder what a true top speed is on the Mischief with a 70?
c_mccann posted 02-24-2005 01:25 PM ET (US)
Is that 115 at the prop? Sounds like fun, anyway.
oceanloverny posted 02-24-2005 01:29 PM ET (US)
According to NADA a 1988 70-HP Mercury motor is 265-lbs. and the 1988 115 is 312-lbs. I truly don't think weight would be a problem.
The current speed as rigged with the 70 is just less than of 50-MPH stock. The 1988 115-HP motor that I am thinking of putting on is all original. It only has about 50 hours on it. Runs so perfect and quiet it sounds like a four-stroke.
I don't think [a MISCHIEF 15] would be that out of control with the 115. The boat that the motor is coming from is a tiny 16-foot Glastron.
Are the wiring harnesses interchangeable between a 70 and a 115 of the same year?
Thanks to all for your input, I really appreciate it!
BOB KEMMLER JR posted 02-24-2005 01:38 PM ET (US)
Is that speed per GPS or a fishfinder? I bet you have a easy swap on your hands, and the harnesses will snap right together, maybe even throttle and shift controls, too.I 'd love to see pics if you have them
oceanloverny posted 02-24-2005 06:51 PM ET (US)
Bob--send me an email and I'll send you some pic's. You wouldn't believe the condition it in.
Jeff
oceanloverny@aol.com
Whaler Lover2 posted 02-24-2005 07:34 PM ET (US)
Did you just buy this boat from a guy near Buffalo NY?
BOB KEMMLER JR posted 02-24-2005 08:17 PM ET (US)
Nah he's a REAL New Yorker, not one of those upstate snake oil salesmen. I am looking forward to the pics and information.
jimh posted 02-25-2005 08:45 AM ET (US)
[Moved thread]
jimh posted 02-25-2005 09:06 AM ET (US)
Boston Whaler hulls were not really designed for high speed operation. The hulls are built with strong materials and can tolerate some abuse.
Raising the horsepower to 115 from 70 is an increase of 64-percent above maximum. To put that in perspective, this is the same proportion as taking a an OUTRAGE-22 which is rated for 240-HP and putting 400-HP on the transom.
jimh posted 02-25-2005 09:11 AM ET (US)
Perhaps your mention of "whaler reference" refers to my article:
Maximum Rated Horsepower
http://continuouswave.com/whaler/reference/ratedHP.html
In the section, How is the maximum rated power determined?, I explain the calculations for maximum horsepower required in the federal regulations. This includes the allowance that the rated horsepower may be rounded up to the nearest "5".
When your calculations produced a result of 83-HP, rounding up to the nearest five means that you could round up to 85. Your invention that you could be allowed to round up to 90-HP has no basis in the regulations.
brisboats posted 02-25-2005 10:01 AM ET (US)
Jeff, Is the motor an inline 6? If so thats just the conversion Bob and I have been talking about. The weight is a non issue and the control plug , throttle and shift is the same. I would look into dual cable steering or a hydraulic setup always wear the safety lanyard and start dialing it in. Yeah we know Whalers aren't performance boats but it is fun making them go faster. That motor on my 74 smirkless gets the boat into the mid 50's easily.
Blah blah blah and Shame on you Jeff for wanting to so grossly overpower a boat and much less a classic Whaler. Hmmm... just a passing thought but gee doesn't LHG have two of these black beautys on the back of an outrage 18? Thats 230hp on a hull rated at 150hp max. I am not very good at math, but believe that is almost 54% above the maximum rated hp.
Brian
BOB KEMMLER JR posted 02-25-2005 10:05 AM ET (US)
That may be true Jim,but how much more top end do you think the boat will really get from that jump?From a 70 to a 115,i bet 10 mph would be a high expectation,but part throttle and loaded it would be much improved.If i could put a 200 on the back,i'd do it in a heartbeat.that doesn't mean i'd ever get the right water conditions to hold it at WOT throttle for long.I like the idea of being able to make short blasts to a "safe for water conditions" speed and being able to baby the motor for general cruising.Plus it's just plain bragging rights lol
BOB KEMMLER JR posted 02-25-2005 10:26 AM ET (US)
if i had the cash to waste,this would find it's way onto the back of a mischief.
http://www.mercurymarine.com/sst_120s2000_race
Buckda posted 02-25-2005 10:40 AM ET (US)
Bris -
Actually, it's only about 22% overpowered, given that the federal regulations allow 180 HP max on the 18' Outrage, given the formula.
With twins, the stability is somewhat increased....however anyone who's had the pleasure of riding in LHG's rocket sled know that his setup is a LOT of power for that boat.
where2 posted 02-25-2005 12:24 PM ET (US)
Bob, Why stop at such low Horsepower numbers. Jump on up to a gas turbine Mercury... http://www.texs.com/magazine/tsg_13.htm It's a little funny looking at first, but after you find the 400Hp rating, who cares what it looks like. The powerhead only weighs 140lbs, what's a normal gearcase and mid section weigh?
BOB KEMMLER JR posted 02-25-2005 01:04 PM ET (US)
WOW! I bet i know why they call that guy "Chub",after driving that thing i bet anyone could be called "Chub" lol I have to work on my photoshop skills now and graft that on the back of a Mischief
The Judge posted 02-25-2005 01:13 PM ET (US)
I spent a week on a 1978 15' with a 115 Ocean runner and the boat did not have one stress crack and sat OK in the water.....go for it if you can handle a upper 50's mph ride.
linust posted 02-25-2005 02:14 PM ET (US)
Bob Kemmler, you're not far off factory thinking...following along Jimh's calcs, remember that Whaler did give the 22 WD hull a 400hp rating one year!
Much as I'm a gearhead and like speed, this combo does sound scary. If you do go for it, I'll second Bob's suggestions on helmet and life insurance ;)
LHG posted 02-25-2005 03:23 PM ET (US)
You guys must be lot younger than I am, and I powered that 18 Outrage as I did 19 years ago, with one of the enignes coming off my previous 16' Nauset! When you're talking over-powering of any boat, you have to talk engine brand as age of engine (powerhead or prop rated), not just advertized HP. The weight of my 20", 1985 Merc in-line 6 115's, with power trim, is shown as 305#. Be advised, that in original condition with full compression, etc, these things put out more like 125HP at the prop. Mine were recently prop dyno'd at those HP figures, both of them, and they're 20 years old.
A Merc technician also told me the 2-stroke Merc 90 (3 cylinder version) really puts out more like 100 HP. If you look in the Montauk 170 performance graphs, you will see this improved perfromance over the Opti and 4-stroke, which are true 90Hp engines.
Having recently had my first ever ride in a 15 Sport, I can't imagine that a small hull like that can handle a 125HP Merc in-line 6 "tower of power", jacked up and turning 26" Merc chopper props. (Well, maybe ex-racer Sal could!). Sounds like a death wish to me.
I would also recommend re-reading Clark Roberts excellent article on the performance aspects of this hull, published in the reference section. For some reason, it does not appear to be much faster than the 16' hull
BOB KEMMLER JR posted 02-25-2005 04:23 PM ET (US)
so you think i'd be better off going with the 26" chopper prop Larry? ;o)
blkmtrfan posted 02-25-2005 05:30 PM ET (US)
I don't think he will have enough power to turn the 26p chopper, I think a 22p would be a better place to start.
And if you really want to get the motor up high enough to really use the chopper, he will need some sort of low water pickup ...

But really if you want to go fast in a 15 sport you are really going to need to modify the bottom a little, the rounded keel of a whaler is a big part of the "chine walking" problem you all see, the other is the motor is usually way too low. So some sort of "pad" needs to be fitted to the bottom and then you really need to put the boat on a diet and take out everyting but the one seat and the helm, then if you are lucky you might see 60 moh, LOL...
BOB KEMMLER JR posted 02-25-2005 05:33 PM ET (US)
i know your joking,but all that has entered my warped mind lol
blkmtrfan posted 02-25-2005 06:01 PM ET (US)
Yes I am joking, a little, as making a whaler go fast kind of like setting up and SUV for autocross, (nothing bad about whalers or SUV's it is just about intended purpose) but with enough desire anything is possible.
However, just so you know, everything I said is on the right track. I do have a little knowledge of know what it takes to make a outboard pleasure boat go fast, this is one of my boats:
link1
link2
brisboats posted 02-25-2005 06:22 PM ET (US)
It can be done, who will be the first? A guy on the screamandfly forum put a pad on an old Bayliner and with a 85hp Force was in the 50's.
LHG is right on about the late 115 inlines, they are prop rated and the rating is conservative. The pistons (low domed) and compression ratio is identical to the earlier 140hp and they come with a better ignition system. Power to weight even now they are hard to beat. Someone rig one on a Mischief and post some numbers.
Brian
BOB KEMMLER JR posted 02-25-2005 06:26 PM ET (US)
sweet rig.Not that i would do it,but can you get those Mercury race outboards in a 20" shaft?like the sst/120?
BOB KEMMLER JR posted 02-25-2005 06:27 PM ET (US)
I have to find a boat first bryan,unless i try to ride the outboard cowboy style lol
brisboats posted 02-25-2005 06:32 PM ET (US)
Now I would like to see that... giddeeeeup. Well I have heard that the nicest remaining Mischief on the planet may still be available,lol.
blkmtrfan posted 02-25-2005 07:52 PM ET (US)
Bob the motor on my boat is a 20" mid length and from mercury racing, the "consuber division" It is called the 2.5 EFI sport, 2005 is the last year of production and it puts out 280 prop shaft HP. I think it might be a little much for a mischief.

But there were many raccing versions of the an old inline 6, be pretty easy to get one to make 150 HP.
Go over to screamandfly and do a search, you will find a budch of good info in inlines
blkmtrfan posted 02-25-2005 07:57 PM ET (US)
BTW I would like to appologize for my bad spelling, it really isn't my spelling so much as my bad typing, I get going really fast then I post itm, then see my mistakes and I can't go back and edit, LOL
Sorry guys ...
BOB KEMMLER JR posted 02-25-2005 08:02 PM ET (US)
they have a 180 hp motor that weighs 275lbs,but it's listed as a 12" shaft,that would be the "dream" powerplant.
blkmtrfan posted 02-25-2005 08:24 PM ET (US)
You might be able to make the 12" work just put it on a different mid
BOB KEMMLER JR posted 02-25-2005 08:39 PM ET (US)
i would be afraid to find out how much that thing even cost lol
HUSKERDU posted 02-26-2005 12:32 PM ET (US)
You guys are Mischievous!lol. I am currently in the process of throwing too much money at a 1989 Mischief hull. Glasswork, new interior, new oem cover, gauges, jackplate, etc.
I was planning to repower with the 90 Rude Etek, but this appears to be a plain vanilla upgrade in this discussion! Where might someone find a nice vintage merc for this rig? Bob? Anyone? Thanks Jim. PS I don't like ebay!
blkmtrfan posted 02-26-2005 02:18 PM ET (US)
Bob I am sure you are right about the price of a full on race motor, plus if you look at the fine print, they don't warrany the race stuff...
Really I think a nice merc inline6 or an omc V-4
For used motors check out:
http://forums.screamandfly.com/forums/forumdisplay.php?f=3
BOB KEMMLER JR posted 02-26-2005 02:49 PM ET (US)
thanks for the link to that forum.will put it on my list.might be a great place for tips,parts etc.I also call dibs on the name "suck my wake" for my boat lol
jimh posted 02-26-2005 05:52 PM ET (US)
[Fixed long URI]
jimh posted 02-26-2005 06:08 PM ET (US)
Re the difference between having 230-HP on an OUTRAGE 18 compared to having 115-HP on a MISCHIEF 15:
The LHG Outrage 18 is a vee-hull and seems to be able to remain fairly stable above 50-MPH, although it is rarely ever driven to those speeds. The boat has proven its long-term ability to handle the power, and there is little question about its sea keeping ability.
BOB KEMMLER JR posted 02-26-2005 06:50 PM ET (US)
well i guess we won't know much till a few of us do it.I heard the same types of things with my Rage swap,just made me want to finish it even more(nothing like nay sayers to get the creative juices flowing).Don't forget the Mischief in Sausilito with a built 140 merc inline on the back.I'm not sure of how his boat is setup,but he did say it was for expierienced high performance boat drivers only,and could be dangerous in the wrong hands.If it's unstable,i guess that just means 3/4 throttle will be fine,and loaded down it will be ideal.
where2 posted 02-26-2005 07:17 PM ET (US)
Bob, you should have kept your Rage. It had a built-in pad, and you could have added a little more when you reworked that filler block where the jet pump came out... Then if we looked long enough, we could have located some sort of racing engine to mount on it...
BOB KEMMLER JR posted 02-26-2005 07:56 PM ET (US)
I think the man i sold it to,just might do that eventually,he's already mentioned a 90hp finding it's way on the back one day.I can't wait to see when he's done with the glass and gel coat work,should look factory then.It's just in my nature to do things differently from the crowd.I have a Dodge Omni with about 280 hp,why?why not ;o)
Binkie posted 02-26-2005 09:42 PM ET (US)
Remember, if you ain`t skeered, you ain`t overpowered!
blkmtrfan posted 02-28-2005 10:51 AM ET (US)
where2 I was kind of thinking the same thing about the rage conversion. A guy could make a sweet pad when you took the jet intake out and those were reated up to 175HP humm....
Could be a wild ride for sure

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Author	Topic: MISCHIEF 15: Re-power Above Maximum Rated
oceanloverny	posted 02-24-2005 10:35 AM ET (US) My 1988 Mischief 15 is currently powered by a 70-HP outboard. Based on calculations from "whaler reference" [?] the result is 83-HP. Rounding up by 5-ish would give 90-HP. Am I making a big mistake by putting a 1988 115-HP? that I have on it. Has anyone first hand experience with a 115-HP on [this] hull? Thank you.
skiff	posted 02-24-2005 11:15 AM ET (US) Whoa, a 115? I have a Mischief with a 70-HP Yamaha, and it has plenty of push. I'm sure you've checked the extra weight, but I'd think that the transom might sit a bit too low with that size rig on the stern. I use my boat on the ocean primarily, but on a lake, where I can finally get her up to top speed with the 70-HP, I detect a bit of chine walk--God's way of telling me to slow down. With a 115, I'd think you'd get going faster than that hull should mathmatically be driven.
dscew	posted 02-24-2005 11:16 AM ET (US) I think the result would be a stern heavy missile, and I would [not] want to be on the water when it was at full throttle. Way overpowered, IMHO.
jeffs22outrage	posted 02-24-2005 11:42 AM ET (US) When I was growing up, we had a 75-HP Mercury--5-HP above recommended--on our 15 SUPE SPORT. It would hit 60-MPH with ease with one person in it, a friend in the marina called it the ICBM (intercontinental ballistic missile). I scared myself a couple times at WOT getting a gust of wind under the bow, boat would lift and chine walk like crazy. At WOT the hull was almost completely out of the water. The boat with one person and a full tank of gas had just inches of freeboard, I think the 115-HP will sink the transom. My father has 90-HP on his MONTAUK and it will do 50-MPH or more, and that boat is longer and heavier than the 15-foot. Over powering a little whaler is more likely to get out of hand than over powering a boat like an Outrage.
BOB KEMMLER JR	posted 02-24-2005 12:26 PM ET (US) Oceanlover--What make of 115 were you thinking of using? The older 6-cylinder Mercury motors were only 295-lbs., so the weight shouldn't be that much of a factor. The mischief is a little heavier as well, so it should take a little more horsepower to get the same top speed as a standard with a 70 on it. I say put a 6-inch jackplate on the back, get hydraulic steering, low water pickup nose cone, surface running prop, hot foot throttle, foot T&T unit, helmet, life insurance. and pick a dead flat day on the sound. You can also offset some of the transom weight by running a larger fuel tank under the front deck and placing the battery up front. I wonder what a true top speed is on the Mischief with a 70?
c_mccann	posted 02-24-2005 01:25 PM ET (US) Is that 115 at the prop? Sounds like fun, anyway.
oceanloverny	posted 02-24-2005 01:29 PM ET (US) According to NADA a 1988 70-HP Mercury motor is 265-lbs. and the 1988 115 is 312-lbs. I truly don't think weight would be a problem. The current speed as rigged with the 70 is just less than of 50-MPH stock. The 1988 115-HP motor that I am thinking of putting on is all original. It only has about 50 hours on it. Runs so perfect and quiet it sounds like a four-stroke. I don't think [a MISCHIEF 15] would be that out of control with the 115. The boat that the motor is coming from is a tiny 16-foot Glastron. Are the wiring harnesses interchangeable between a 70 and a 115 of the same year? Thanks to all for your input, I really appreciate it!
BOB KEMMLER JR	posted 02-24-2005 01:38 PM ET (US) Is that speed per GPS or a fishfinder? I bet you have a easy swap on your hands, and the harnesses will snap right together, maybe even throttle and shift controls, too.I 'd love to see pics if you have them
oceanloverny	posted 02-24-2005 06:51 PM ET (US) Bob--send me an email and I'll send you some pic's. You wouldn't believe the condition it in. Jeff oceanloverny@aol.com
Whaler Lover2	posted 02-24-2005 07:34 PM ET (US) Did you just buy this boat from a guy near Buffalo NY?
BOB KEMMLER JR	posted 02-24-2005 08:17 PM ET (US) Nah he's a REAL New Yorker, not one of those upstate snake oil salesmen. I am looking forward to the pics and information.
jimh	posted 02-25-2005 08:45 AM ET (US) [Moved thread]
jimh	posted 02-25-2005 09:06 AM ET (US) Boston Whaler hulls were not really designed for high speed operation. The hulls are built with strong materials and can tolerate some abuse. Raising the horsepower to 115 from 70 is an increase of 64-percent above maximum. To put that in perspective, this is the same proportion as taking a an OUTRAGE-22 which is rated for 240-HP and putting 400-HP on the transom.
jimh	posted 02-25-2005 09:11 AM ET (US) Perhaps your mention of "whaler reference" refers to my article: Maximum Rated Horsepower http://continuouswave.com/whaler/reference/ratedHP.html In the section, How is the maximum rated power determined?, I explain the calculations for maximum horsepower required in the federal regulations. This includes the allowance that the rated horsepower may be rounded up to the nearest "5". When your calculations produced a result of 83-HP, rounding up to the nearest five means that you could round up to 85. Your invention that you could be allowed to round up to 90-HP has no basis in the regulations.
brisboats	posted 02-25-2005 10:01 AM ET (US) Jeff, Is the motor an inline 6? If so thats just the conversion Bob and I have been talking about. The weight is a non issue and the control plug , throttle and shift is the same. I would look into dual cable steering or a hydraulic setup always wear the safety lanyard and start dialing it in. Yeah we know Whalers aren't performance boats but it is fun making them go faster. That motor on my 74 smirkless gets the boat into the mid 50's easily. Blah blah blah and Shame on you Jeff for wanting to so grossly overpower a boat and much less a classic Whaler. Hmmm... just a passing thought but gee doesn't LHG have two of these black beautys on the back of an outrage 18? Thats 230hp on a hull rated at 150hp max. I am not very good at math, but believe that is almost 54% above the maximum rated hp. Brian
BOB KEMMLER JR	posted 02-25-2005 10:05 AM ET (US) That may be true Jim,but how much more top end do you think the boat will really get from that jump?From a 70 to a 115,i bet 10 mph would be a high expectation,but part throttle and loaded it would be much improved.If i could put a 200 on the back,i'd do it in a heartbeat.that doesn't mean i'd ever get the right water conditions to hold it at WOT throttle for long.I like the idea of being able to make short blasts to a "safe for water conditions" speed and being able to baby the motor for general cruising.Plus it's just plain bragging rights lol
BOB KEMMLER JR	posted 02-25-2005 10:26 AM ET (US) if i had the cash to waste,this would find it's way onto the back of a mischief. http://www.mercurymarine.com/sst_120s2000_race
Buckda	posted 02-25-2005 10:40 AM ET (US) Bris - Actually, it's only about 22% overpowered, given that the federal regulations allow 180 HP max on the 18' Outrage, given the formula. With twins, the stability is somewhat increased....however anyone who's had the pleasure of riding in LHG's rocket sled know that his setup is a LOT of power for that boat.
where2	posted 02-25-2005 12:24 PM ET (US) Bob, Why stop at such low Horsepower numbers. Jump on up to a gas turbine Mercury... http://www.texs.com/magazine/tsg_13.htm It's a little funny looking at first, but after you find the 400Hp rating, who cares what it looks like. The powerhead only weighs 140lbs, what's a normal gearcase and mid section weigh?
BOB KEMMLER JR	posted 02-25-2005 01:04 PM ET (US) WOW! I bet i know why they call that guy "Chub",after driving that thing i bet anyone could be called "Chub" lol I have to work on my photoshop skills now and graft that on the back of a Mischief
The Judge	posted 02-25-2005 01:13 PM ET (US) I spent a week on a 1978 15' with a 115 Ocean runner and the boat did not have one stress crack and sat OK in the water.....go for it if you can handle a upper 50's mph ride.
linust	posted 02-25-2005 02:14 PM ET (US) Bob Kemmler, you're not far off factory thinking...following along Jimh's calcs, remember that Whaler did give the 22 WD hull a 400hp rating one year! Much as I'm a gearhead and like speed, this combo does sound scary. If you do go for it, I'll second Bob's suggestions on helmet and life insurance ;)
LHG	posted 02-25-2005 03:23 PM ET (US) You guys must be lot younger than I am, and I powered that 18 Outrage as I did 19 years ago, with one of the enignes coming off my previous 16' Nauset! When you're talking over-powering of any boat, you have to talk engine brand as age of engine (powerhead or prop rated), not just advertized HP. The weight of my 20", 1985 Merc in-line 6 115's, with power trim, is shown as 305#. Be advised, that in original condition with full compression, etc, these things put out more like 125HP at the prop. Mine were recently prop dyno'd at those HP figures, both of them, and they're 20 years old. A Merc technician also told me the 2-stroke Merc 90 (3 cylinder version) really puts out more like 100 HP. If you look in the Montauk 170 performance graphs, you will see this improved perfromance over the Opti and 4-stroke, which are true 90Hp engines. Having recently had my first ever ride in a 15 Sport, I can't imagine that a small hull like that can handle a 125HP Merc in-line 6 "tower of power", jacked up and turning 26" Merc chopper props. (Well, maybe ex-racer Sal could!). Sounds like a death wish to me. I would also recommend re-reading Clark Roberts excellent article on the performance aspects of this hull, published in the reference section. For some reason, it does not appear to be much faster than the 16' hull
BOB KEMMLER JR	posted 02-25-2005 04:23 PM ET (US) so you think i'd be better off going with the 26" chopper prop Larry? ;o)
blkmtrfan	posted 02-25-2005 05:30 PM ET (US) I don't think he will have enough power to turn the 26p chopper, I think a 22p would be a better place to start. And if you really want to get the motor up high enough to really use the chopper, he will need some sort of low water pickup ... But really if you want to go fast in a 15 sport you are really going to need to modify the bottom a little, the rounded keel of a whaler is a big part of the "chine walking" problem you all see, the other is the motor is usually way too low. So some sort of "pad" needs to be fitted to the bottom and then you really need to put the boat on a diet and take out everyting but the one seat and the helm, then if you are lucky you might see 60 moh, LOL...
BOB KEMMLER JR	posted 02-25-2005 05:33 PM ET (US) i know your joking,but all that has entered my warped mind lol
blkmtrfan	posted 02-25-2005 06:01 PM ET (US) Yes I am joking, a little, as making a whaler go fast kind of like setting up and SUV for autocross, (nothing bad about whalers or SUV's it is just about intended purpose) but with enough desire anything is possible. However, just so you know, everything I said is on the right track. I do have a little knowledge of know what it takes to make a outboard pleasure boat go fast, this is one of my boats: link1 link2
brisboats	posted 02-25-2005 06:22 PM ET (US) It can be done, who will be the first? A guy on the screamandfly forum put a pad on an old Bayliner and with a 85hp Force was in the 50's. LHG is right on about the late 115 inlines, they are prop rated and the rating is conservative. The pistons (low domed) and compression ratio is identical to the earlier 140hp and they come with a better ignition system. Power to weight even now they are hard to beat. Someone rig one on a Mischief and post some numbers. Brian
BOB KEMMLER JR	posted 02-25-2005 06:26 PM ET (US) sweet rig.Not that i would do it,but can you get those Mercury race outboards in a 20" shaft?like the sst/120?
BOB KEMMLER JR	posted 02-25-2005 06:27 PM ET (US) I have to find a boat first bryan,unless i try to ride the outboard cowboy style lol
brisboats	posted 02-25-2005 06:32 PM ET (US) Now I would like to see that... giddeeeeup. Well I have heard that the nicest remaining Mischief on the planet may still be available,lol.
blkmtrfan	posted 02-25-2005 07:52 PM ET (US) Bob the motor on my boat is a 20" mid length and from mercury racing, the "consuber division" It is called the 2.5 EFI sport, 2005 is the last year of production and it puts out 280 prop shaft HP. I think it might be a little much for a mischief. But there were many raccing versions of the an old inline 6, be pretty easy to get one to make 150 HP. Go over to screamandfly and do a search, you will find a budch of good info in inlines
blkmtrfan	posted 02-25-2005 07:57 PM ET (US) BTW I would like to appologize for my bad spelling, it really isn't my spelling so much as my bad typing, I get going really fast then I post itm, then see my mistakes and I can't go back and edit, LOL Sorry guys ...
BOB KEMMLER JR	posted 02-25-2005 08:02 PM ET (US) they have a 180 hp motor that weighs 275lbs,but it's listed as a 12" shaft,that would be the "dream" powerplant.
blkmtrfan	posted 02-25-2005 08:24 PM ET (US) You might be able to make the 12" work just put it on a different mid
BOB KEMMLER JR	posted 02-25-2005 08:39 PM ET (US) i would be afraid to find out how much that thing even cost lol
HUSKERDU	posted 02-26-2005 12:32 PM ET (US) You guys are Mischievous!lol. I am currently in the process of throwing too much money at a 1989 Mischief hull. Glasswork, new interior, new oem cover, gauges, jackplate, etc. I was planning to repower with the 90 Rude Etek, but this appears to be a plain vanilla upgrade in this discussion! Where might someone find a nice vintage merc for this rig? Bob? Anyone? Thanks Jim. PS I don't like ebay!
blkmtrfan	posted 02-26-2005 02:18 PM ET (US) Bob I am sure you are right about the price of a full on race motor, plus if you look at the fine print, they don't warrany the race stuff... Really I think a nice merc inline6 or an omc V-4 For used motors check out: http://forums.screamandfly.com/forums/forumdisplay.php?f=3
BOB KEMMLER JR	posted 02-26-2005 02:49 PM ET (US) thanks for the link to that forum.will put it on my list.might be a great place for tips,parts etc.I also call dibs on the name "suck my wake" for my boat lol
jimh	posted 02-26-2005 05:52 PM ET (US) [Fixed long URI]
jimh	posted 02-26-2005 06:08 PM ET (US) Re the difference between having 230-HP on an OUTRAGE 18 compared to having 115-HP on a MISCHIEF 15: The LHG Outrage 18 is a vee-hull and seems to be able to remain fairly stable above 50-MPH, although it is rarely ever driven to those speeds. The boat has proven its long-term ability to handle the power, and there is little question about its sea keeping ability.
BOB KEMMLER JR	posted 02-26-2005 06:50 PM ET (US) well i guess we won't know much till a few of us do it.I heard the same types of things with my Rage swap,just made me want to finish it even more(nothing like nay sayers to get the creative juices flowing).Don't forget the Mischief in Sausilito with a built 140 merc inline on the back.I'm not sure of how his boat is setup,but he did say it was for expierienced high performance boat drivers only,and could be dangerous in the wrong hands.If it's unstable,i guess that just means 3/4 throttle will be fine,and loaded down it will be ideal.
where2	posted 02-26-2005 07:17 PM ET (US) Bob, you should have kept your Rage. It had a built-in pad, and you could have added a little more when you reworked that filler block where the jet pump came out... Then if we looked long enough, we could have located some sort of racing engine to mount on it...
BOB KEMMLER JR	posted 02-26-2005 07:56 PM ET (US) I think the man i sold it to,just might do that eventually,he's already mentioned a 90hp finding it's way on the back one day.I can't wait to see when he's done with the glass and gel coat work,should look factory then.It's just in my nature to do things differently from the crowd.I have a Dodge Omni with about 280 hp,why?why not ;o)
Binkie	posted 02-26-2005 09:42 PM ET (US) Remember, if you ain`t skeered, you ain`t overpowered!
blkmtrfan	posted 02-28-2005 10:51 AM ET (US) where2 I was kind of thinking the same thing about the rage conversion. A guy could make a sweet pad when you took the jet intake out and those were reated up to 175HP humm.... Could be a wild ride for sure