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Author Topic:   OUTRAGE 25: Re-power with Twin OptiMax

imarine posted 03-19-2006 03:21 AM ET (US)
I would like to make an informed decision on powering a classic OUTRAGE 25 with brand new twin Mercury OptiMax outboard motors. I would like to choose between twin 175-HP or twin 225-HP OptiMax motors with DTS. I need to know:
Can the standard notched transom (no Whaler Drive) handle the weight?
Is the increase in horsepower (2 X 175 vs 2 X 225) enough to compensate in performance for the engine load?
Are there other concerns I am overlooking?( Accomplishing the installation will not be an problem.)
Shed light on.
LHG posted 03-19-2006 05:02 PM ET (US)
Tell us how you are going to accomplish counter rotating 25" twins on the 20" notched transom. Jackplates?
Once you solve the above, power choice should depend on how fast you want to go. (assuming no bottom paint)
175 Opti's: 55
200 Opti's: 64
225 Opti's: 68
Those 3.0 liter Mercs are a lot of power for the hull, but the DTS would be nice. I'd get the 200's, as the 3.0 liter engines are quieter running. 497# weight (each) no problem. You'll be loafing along at low RPM most of the time. Clear the power with your insurance agent also.
Here's mine at the Lauderdale Marina dock: http://photobucket.com/albums/v429/lgoltz/Outrage%2025/?action=view& current=Scan0050.jpg
With 200 EFI's it runs 62. For top end, recommend you use Tempest Plus props, or Rev 4's. Or wait for the new Enertia's. Might also consider waiting for the 2007 upgraded Optimax's.
imarine posted 03-20-2006 08:31 PM ET (US)
Thanks for the informative reply. Your pics are truely great and the potential speed is appealing.
I did not check the height of the transom which makes perfect sense to do in hindsight. Originally it had twin 140 (johnson I believe) and after we had a single johnson 225 (with 25" foot)on it and that was in the water fine so I assumed twins would work just as well as far as height is concerned.
Do you foresee any benefit of using a bracket (armstrong or otherwise) over jack plates?
We should have removed the engine in the morning and I will measure the height of the transom. keep you posted. The hull is being stripped to be re-sprayed so I believe I will be in time for the upgraded Optis although a rep from Merc said I could get the upgraded engines now. I have about 4 weeks to go anyway as the hull requires no major work.
LHG posted 03-20-2006 08:52 PM ET (US)
You will need jackplates (the more setback the better) to install 25" CR engines. A 26" setback full transom bracket will cost a lot more, but can be nicely fitted. Mine is an Armstrong.
Rite Hite (rmind.com) makes nice black painted HD jackplate units, (6, 8 and 10" setback) but I am a little concerned how well they will hold up in salt. I have one on another boat, and the paint is flaking around the side tightening bolts, from the tightening action. But they are cleanest looking, best designed units on the market, I think.
http://photobucket.com/albums/v429/lgoltz/Outrage%2021/?action=view& current=DSCN1361.jpg
http://photobucket.com/albums/v429/lgoltz/Outrage%2021/?action=view& current=Scan0010.jpg .
jimh posted 03-20-2006 10:32 PM ET (US)
According to Boston Whaler specifications, an OUTRAGE 25 with the standard outboard or notched transom uses 20-inch shaft engines for twins, and a 25-inch shaft for a single.
I have written a lengthy article in the Reference section which discusses the advantages of using engine set back brackets. You may find that it will answer your question:
Engine Brackets
"This article describes the improvements gained by mounting outboard engines on setback brackets and how such brackets were offered from Boston Whaler in the period of 1983 to 1993. (A companion article shows in detail the fitting of an aftermarket setback bracket to a Whaler with standard transom and the advantages this has produced, as well as details about the use of hydraulic steering, an upgrade frequently required when engines are mounted on brackets.)"
http://continuouswave.com/whaler/reference/engineBrackets.html
The DTS option is available only on the 200 and 225-HP OptiMax engines.
Peter posted 03-21-2006 08:38 AM ET (US)
I think the performance predictions for a notched transom 25 Outrage given here are quite a bit on the optimistic side! According to Crouch's speed prediction formula using a hull factor of 200 (generous for a standard issue notched transom 25 Outrage) and a total weight of 5,500 lbs (weight taken from the Performance Prediction Table in the Reference Section), 350, 400 and 450 HP on the transom should produce 51, 54 and 57 MPH, respectively.
To be able to go 68 MPH in a standard notched transom Outrage 25, as appears to be suggested here, requires either: (1) 650 HP, a hull factor of 200 and a weight of 5500 lbs, (2) 450 HP, a hull factor of 237 and a weight of 5500 lbs or (3) 450 HP, a hull factor of 200 and a weight not to exceed 3900 lbs. Items (1) and (3) are not likely possibilities. Item (2) may be possible through the use of a set back bracket which would change the hydrodynamics of the boat thereby increasing the hull factor, but it is likely that there would be a trade off on some aspects of the current ride with the weight of the outboards on the transom being amplified by the moment arm of the set back bracket.
LHG posted 03-21-2006 01:22 PM ET (US)
Peter, what's my hull factor?
25 Outrage full transom (heavier than regular Outrage)
Mills canvas and radar arch
No bottom paint
100# bracket
twin 200 Mercs (the old fashioned, stinky kind), 415# each, Rev 4 props
1/2 tank of fuel
Speed 62 MPH

Peter posted 03-21-2006 02:10 PM ET (US)
My guess is your rig's total weight is still close to 5,500 lbs with a 1/2 tank of fuel. Assuming the motors produce 200 HP each, the hull factor works out to about 230. If the motors produce 220 HP each, then the hull factor drops down to about 220. So I'd say your hull factor is somewhere between 220 and 230.
LHG posted 03-21-2006 02:25 PM ET (US)
I have noticed the twin Rev 4 props have tremendous overall hull lift, including stern lift, on this relatively lightweight hull. This seems to increase hull factor, and aids top end speed.
Running above 50, there is no sidespray coming off the hull at all. All spray is angling back off the transom, parallel to the wake. The Laser II props did not give me this condition, with nowhere near the stern lift.
So what I am saying is that Crouch's formula needs to factor in stern lift from props to be anywhere near accurate. Props like the Rev 4's would tend to increase hull factor over conventional props.
Peter posted 03-21-2006 03:00 PM ET (US)
I've run a wide variety of propellers on my boat including the Rev 4s and the Rev 4s were not the fastest so there is no magic Crouch formula defying power coming from the Rev 4s. The only thing a good propeller does over a bad propeller is turn more of the available prop shaft horsepower into usable forward motion producing thrust. Because HP is part of Crouch's formula, the propeller is already accounted for in the sense that the HP number used in the formula would be increased slightly relative to a propeller with a lesser efficiency.
There is no magic here. An ordinary notched transom 25 Outrage with 450 HP is not going to reach 68 MPH except possibly when towed on a trailer.

LHG posted 03-21-2006 03:15 PM ET (US)
My point was the additional LIFT reduces hull friction, giving more speed from same HP. Not talking about engine HP exiting props. I think that big'ol 27WD is too heavy to gain much lift from the Rev-4's. But a non-WD 25 does.
Someone should plug these numbers into the Merc prop calculator. I considered a pair of 225 EFI's for my Outrage, and the prop charts were giving me at least 68 MPH and 23" pitch running through the 1.76 gears. Actually on my boat, I would now be quite happy with a pair of 175's
Peter posted 03-21-2006 03:58 PM ET (US)
Conventional boats that don't have motors hanging 30 inches off the transom usually use highly raked bow lifting props not stern lifting props like the Rev 4 to achieve high speeds. In your case, however, you have so much weight hanging 30 inches off the stern of the boat that it might be possible that a Rev 4 performs better. I speculate that the stern lifting tendency of the Rev 4s could be keeping your stern from digging in too much as it probably would with bow lifting propellers. That stern lift/bow lift trade off would be different for a notched transom 25 Outrage.
I think the only thing performance wise left to do on your old 25 Outrage is to give it a day-glo air brushed flame Awlgrip paint job and a purple steering wheel. ;)

LHG posted 03-21-2006 08:07 PM ET (US)
Actually, Peter, I've been considering one of those paint jobs. As a matter of fact, I've contacted Evinrude for the name of their HO graphics flag designer, who I'm sure could do the gaudiest job possible.

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Author	Topic: OUTRAGE 25: Re-power with Twin OptiMax
imarine	posted 03-19-2006 03:21 AM ET (US) I would like to make an informed decision on powering a classic OUTRAGE 25 with brand new twin Mercury OptiMax outboard motors. I would like to choose between twin 175-HP or twin 225-HP OptiMax motors with DTS. I need to know: Can the standard notched transom (no Whaler Drive) handle the weight? Is the increase in horsepower (2 X 175 vs 2 X 225) enough to compensate in performance for the engine load? Are there other concerns I am overlooking?( Accomplishing the installation will not be an problem.) Shed light on.
LHG	posted 03-19-2006 05:02 PM ET (US) Tell us how you are going to accomplish counter rotating 25" twins on the 20" notched transom. Jackplates? Once you solve the above, power choice should depend on how fast you want to go. (assuming no bottom paint) 175 Opti's: 55 200 Opti's: 64 225 Opti's: 68 Those 3.0 liter Mercs are a lot of power for the hull, but the DTS would be nice. I'd get the 200's, as the 3.0 liter engines are quieter running. 497# weight (each) no problem. You'll be loafing along at low RPM most of the time. Clear the power with your insurance agent also. Here's mine at the Lauderdale Marina dock: http://photobucket.com/albums/v429/lgoltz/Outrage%2025/?action=view& current=Scan0050.jpg With 200 EFI's it runs 62. For top end, recommend you use Tempest Plus props, or Rev 4's. Or wait for the new Enertia's. Might also consider waiting for the 2007 upgraded Optimax's.
imarine	posted 03-20-2006 08:31 PM ET (US) Thanks for the informative reply. Your pics are truely great and the potential speed is appealing. I did not check the height of the transom which makes perfect sense to do in hindsight. Originally it had twin 140 (johnson I believe) and after we had a single johnson 225 (with 25" foot)on it and that was in the water fine so I assumed twins would work just as well as far as height is concerned. Do you foresee any benefit of using a bracket (armstrong or otherwise) over jack plates? We should have removed the engine in the morning and I will measure the height of the transom. keep you posted. The hull is being stripped to be re-sprayed so I believe I will be in time for the upgraded Optis although a rep from Merc said I could get the upgraded engines now. I have about 4 weeks to go anyway as the hull requires no major work.
LHG	posted 03-20-2006 08:52 PM ET (US) You will need jackplates (the more setback the better) to install 25" CR engines. A 26" setback full transom bracket will cost a lot more, but can be nicely fitted. Mine is an Armstrong. Rite Hite (rmind.com) makes nice black painted HD jackplate units, (6, 8 and 10" setback) but I am a little concerned how well they will hold up in salt. I have one on another boat, and the paint is flaking around the side tightening bolts, from the tightening action. But they are cleanest looking, best designed units on the market, I think. http://photobucket.com/albums/v429/lgoltz/Outrage%2021/?action=view& current=DSCN1361.jpg http://photobucket.com/albums/v429/lgoltz/Outrage%2021/?action=view& current=Scan0010.jpg .
jimh	posted 03-20-2006 10:32 PM ET (US) According to Boston Whaler specifications, an OUTRAGE 25 with the standard outboard or notched transom uses 20-inch shaft engines for twins, and a 25-inch shaft for a single. I have written a lengthy article in the Reference section which discusses the advantages of using engine set back brackets. You may find that it will answer your question: Engine Brackets "This article describes the improvements gained by mounting outboard engines on setback brackets and how such brackets were offered from Boston Whaler in the period of 1983 to 1993. (A companion article shows in detail the fitting of an aftermarket setback bracket to a Whaler with standard transom and the advantages this has produced, as well as details about the use of hydraulic steering, an upgrade frequently required when engines are mounted on brackets.)" http://continuouswave.com/whaler/reference/engineBrackets.html The DTS option is available only on the 200 and 225-HP OptiMax engines.
Peter	posted 03-21-2006 08:38 AM ET (US) I think the performance predictions for a notched transom 25 Outrage given here are quite a bit on the optimistic side! According to Crouch's speed prediction formula using a hull factor of 200 (generous for a standard issue notched transom 25 Outrage) and a total weight of 5,500 lbs (weight taken from the Performance Prediction Table in the Reference Section), 350, 400 and 450 HP on the transom should produce 51, 54 and 57 MPH, respectively. To be able to go 68 MPH in a standard notched transom Outrage 25, as appears to be suggested here, requires either: (1) 650 HP, a hull factor of 200 and a weight of 5500 lbs, (2) 450 HP, a hull factor of 237 and a weight of 5500 lbs or (3) 450 HP, a hull factor of 200 and a weight not to exceed 3900 lbs. Items (1) and (3) are not likely possibilities. Item (2) may be possible through the use of a set back bracket which would change the hydrodynamics of the boat thereby increasing the hull factor, but it is likely that there would be a trade off on some aspects of the current ride with the weight of the outboards on the transom being amplified by the moment arm of the set back bracket.
LHG	posted 03-21-2006 01:22 PM ET (US) Peter, what's my hull factor? 25 Outrage full transom (heavier than regular Outrage) Mills canvas and radar arch No bottom paint 100# bracket twin 200 Mercs (the old fashioned, stinky kind), 415# each, Rev 4 props 1/2 tank of fuel Speed 62 MPH
Peter	posted 03-21-2006 02:10 PM ET (US) My guess is your rig's total weight is still close to 5,500 lbs with a 1/2 tank of fuel. Assuming the motors produce 200 HP each, the hull factor works out to about 230. If the motors produce 220 HP each, then the hull factor drops down to about 220. So I'd say your hull factor is somewhere between 220 and 230.
LHG	posted 03-21-2006 02:25 PM ET (US) I have noticed the twin Rev 4 props have tremendous overall hull lift, including stern lift, on this relatively lightweight hull. This seems to increase hull factor, and aids top end speed. Running above 50, there is no sidespray coming off the hull at all. All spray is angling back off the transom, parallel to the wake. The Laser II props did not give me this condition, with nowhere near the stern lift. So what I am saying is that Crouch's formula needs to factor in stern lift from props to be anywhere near accurate. Props like the Rev 4's would tend to increase hull factor over conventional props.
Peter	posted 03-21-2006 03:00 PM ET (US) I've run a wide variety of propellers on my boat including the Rev 4s and the Rev 4s were not the fastest so there is no magic Crouch formula defying power coming from the Rev 4s. The only thing a good propeller does over a bad propeller is turn more of the available prop shaft horsepower into usable forward motion producing thrust. Because HP is part of Crouch's formula, the propeller is already accounted for in the sense that the HP number used in the formula would be increased slightly relative to a propeller with a lesser efficiency. There is no magic here. An ordinary notched transom 25 Outrage with 450 HP is not going to reach 68 MPH except possibly when towed on a trailer.
LHG	posted 03-21-2006 03:15 PM ET (US) My point was the additional LIFT reduces hull friction, giving more speed from same HP. Not talking about engine HP exiting props. I think that big'ol 27WD is too heavy to gain much lift from the Rev-4's. But a non-WD 25 does. Someone should plug these numbers into the Merc prop calculator. I considered a pair of 225 EFI's for my Outrage, and the prop charts were giving me at least 68 MPH and 23" pitch running through the 1.76 gears. Actually on my boat, I would now be quite happy with a pair of 175's
Peter	posted 03-21-2006 03:58 PM ET (US) Conventional boats that don't have motors hanging 30 inches off the transom usually use highly raked bow lifting props not stern lifting props like the Rev 4 to achieve high speeds. In your case, however, you have so much weight hanging 30 inches off the stern of the boat that it might be possible that a Rev 4 performs better. I speculate that the stern lifting tendency of the Rev 4s could be keeping your stern from digging in too much as it probably would with bow lifting propellers. That stern lift/bow lift trade off would be different for a notched transom 25 Outrage. I think the only thing performance wise left to do on your old 25 Outrage is to give it a day-glo air brushed flame Awlgrip paint job and a purple steering wheel. ;)
LHG	posted 03-21-2006 08:07 PM ET (US) Actually, Peter, I've been considering one of those paint jobs. As a matter of fact, I've contacted Evinrude for the name of their HO graphics flag designer, who I'm sure could do the gaudiest job possible.