Montauk E-Tec 90 Performance With & Without Jack Plate

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Author Topic:   Montauk E-Tec 90 Performance With & Without Jack Plate

wstr75 posted 10-25-2010 06:22 PM ET (US)
1987 Montauk
2009 90 hp Evinrude E-Tec
Stiletto 15" Stainless Prop
One 195 pound person. 12 gallons of fuel. Two batteries in center console. Hydraulic steering. GPS measurements.
Observations:
42.3 mph at 5050 RPM without jack plate.
44.5 mph at 5400 RPM with Vance Mfg. 6" manual adjustment jack plate set with motor ventilation plate 3.5 inches above the keel centerline.
There was less porpoising at max. speed with the jack plate.
For peace of mind regarding the water pick-up, I trimmed the motor under a bit and let top speed drop to 41 mph. There was a different prop sound at 44.5 mph with the motor trimmed up than was heard at 41 mph and the motor trimmed down. I was by myself and could not look at the ventilation plate depth when maximum speed was being attained.
Slow speed maneuvering seemed to be better with the jack plate, especially when in reverse. When accelerating from a dead stop with the trim set to the 41 mph speed setting, the boat initially accelerated, then the prop ventilated for maybe a second and then went to work. Hard turns to port and starboard were executed without prop slippage or ventilation.
Bill in NC
wstr75 posted 10-25-2010 06:26 PM ET (US)
Additional information:
Water temperature 72 degrees.
Air temperature 70 degrees
Wind: Not a factor as the speed was the same traversing the lake in both directions.
Bill in NC
Tom W Clark posted 10-25-2010 08:02 PM ET (US)
What was the motor mounting position when it was bolted directly on the transom?
meridian posted 10-25-2010 08:27 PM ET (US)
That was just about the same set-up I had and same speed. I was considering putting a water pressure gauge on the E-Tec since you can't see the tell-tale stream.
wstr75 posted 10-25-2010 09:04 PM ET (US)
Tom,
It was in the top bracket hole, i.e. as low as it would go. Ironically, I told the shop to put it up higher in the next to bottom hole and sent them a link to a CW posting explaining optimal Montauk set-up.. Their response was: "We have done a dozen Montauk re-powers, don't worry, our guy will put it in the optimum position".
I am going to try Tosghib's suggestion and crank it up another inch to 4.5" to see what happens. A tilt gauge and a water pressure gauge may be in order at some point in the future.
The boat still tilts to the left when the motor is tucked under and straightens up when the motor is tilted up. It drives straight ahead without much steering input once the motor is tilted past the yaw/roll to the left stage. Nonetheless, I may fiddle around with the motor rudder trim tab in a future afternoon lake trip.
Bill in NC
Tom W Clark posted 10-26-2010 11:02 AM ET (US)
If the motor had been two hole sup on the transom where it ought have been, the difference would be much smaller or there might not have been any difference in top speed and RPM.
The control in reverse is one benefit of a jackplate that cannot be matched by a motor directly on the transom.
wstr75 posted 10-26-2010 12:32 PM ET (US)
Tom,
I agree. If it had been located two holes up it would likely have the same performance as with the jack plate. I may take the jack plate off next spring as it is another 26 pounds hanging off the back of the boat and put the motor up two holes up as you have recommended.
Bottom line: Don't assume the fellow doing the motor installation knows what is best for your boat/motor/prop combination. Make them do it as per what folks have reported in the CW Performance forum.
Bill in NC
dgoodhue posted 10-26-2010 01:26 PM ET (US)
I would raise the engine in a smaller increments than 1". I started off raise it 1/2" at time then 1/4", 1/8, & 1/16 to dial my boat it. The height your engine will like is very dependent on the propeller your using.
Tohsgib posted 10-26-2010 02:25 PM ET (US)
I still think the plate will make about 2mph difference. In my case(s) I need it for draft, 2" less draft is a big difference crossing the flats.
pcrussell50 posted 10-26-2010 04:02 PM ET (US)
Wow, am I reading a thread in the fast outboard boat forum, (whose name is not given in deference to Jim)? Because that is how a lot of this content is reading. Not saying that's a bad thing, btw. I you are really interested in squeezing the last bit of mph out of your utility/workboat, but don't want to go quite as fully committed as a low water pickup and surface-piercing prop, you might try the well known, effective-if-shadetree, best bang for the buck mod... fill in the top two holes of the water pickup. That way, if they do get uncovered by water because of zealous motor raising, they won't suck air. I don't know exactly what the water pickup scheme looks like on the ETEC, but if it looks like classic OMC/BRP motors, it's worth at least an extra inch of engine raising.
I'll post a link to a great picture of exactly what I am talking about and it lools _really_ tight and professional.
-Peter
Tom W Clark posted 10-26-2010 04:38 PM ET (US)
You don't need to worry about the water intakes; as the motor goes higher, the propeller will loose its grip long before the motor looses its cooling water. We are talking about a Montauk after all.
dg22 posted 10-26-2010 06:19 PM ET (US)
wstr75, In your 1st post, you mentioned other performance benefits from the jack plate like less porpoising of your boat. I would consider everything, before removing.

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Author	Topic: Montauk E-Tec 90 Performance With & Without Jack Plate
wstr75	posted 10-25-2010 06:22 PM ET (US) 1987 Montauk 2009 90 hp Evinrude E-Tec Stiletto 15" Stainless Prop One 195 pound person. 12 gallons of fuel. Two batteries in center console. Hydraulic steering. GPS measurements. Observations: 42.3 mph at 5050 RPM without jack plate. 44.5 mph at 5400 RPM with Vance Mfg. 6" manual adjustment jack plate set with motor ventilation plate 3.5 inches above the keel centerline. There was less porpoising at max. speed with the jack plate. For peace of mind regarding the water pick-up, I trimmed the motor under a bit and let top speed drop to 41 mph. There was a different prop sound at 44.5 mph with the motor trimmed up than was heard at 41 mph and the motor trimmed down. I was by myself and could not look at the ventilation plate depth when maximum speed was being attained. Slow speed maneuvering seemed to be better with the jack plate, especially when in reverse. When accelerating from a dead stop with the trim set to the 41 mph speed setting, the boat initially accelerated, then the prop ventilated for maybe a second and then went to work. Hard turns to port and starboard were executed without prop slippage or ventilation. Bill in NC
wstr75	posted 10-25-2010 06:26 PM ET (US) Additional information: Water temperature 72 degrees. Air temperature 70 degrees Wind: Not a factor as the speed was the same traversing the lake in both directions. Bill in NC
Tom W Clark	posted 10-25-2010 08:02 PM ET (US) What was the motor mounting position when it was bolted directly on the transom?
meridian	posted 10-25-2010 08:27 PM ET (US) That was just about the same set-up I had and same speed. I was considering putting a water pressure gauge on the E-Tec since you can't see the tell-tale stream.
wstr75	posted 10-25-2010 09:04 PM ET (US) Tom, It was in the top bracket hole, i.e. as low as it would go. Ironically, I told the shop to put it up higher in the next to bottom hole and sent them a link to a CW posting explaining optimal Montauk set-up.. Their response was: "We have done a dozen Montauk re-powers, don't worry, our guy will put it in the optimum position". I am going to try Tosghib's suggestion and crank it up another inch to 4.5" to see what happens. A tilt gauge and a water pressure gauge may be in order at some point in the future. The boat still tilts to the left when the motor is tucked under and straightens up when the motor is tilted up. It drives straight ahead without much steering input once the motor is tilted past the yaw/roll to the left stage. Nonetheless, I may fiddle around with the motor rudder trim tab in a future afternoon lake trip. Bill in NC
Tom W Clark	posted 10-26-2010 11:02 AM ET (US) If the motor had been two hole sup on the transom where it ought have been, the difference would be much smaller or there might not have been any difference in top speed and RPM. The control in reverse is one benefit of a jackplate that cannot be matched by a motor directly on the transom.
wstr75	posted 10-26-2010 12:32 PM ET (US) Tom, I agree. If it had been located two holes up it would likely have the same performance as with the jack plate. I may take the jack plate off next spring as it is another 26 pounds hanging off the back of the boat and put the motor up two holes up as you have recommended. Bottom line: Don't assume the fellow doing the motor installation knows what is best for your boat/motor/prop combination. Make them do it as per what folks have reported in the CW Performance forum. Bill in NC
dgoodhue	posted 10-26-2010 01:26 PM ET (US) I would raise the engine in a smaller increments than 1". I started off raise it 1/2" at time then 1/4", 1/8, & 1/16 to dial my boat it. The height your engine will like is very dependent on the propeller your using.
Tohsgib	posted 10-26-2010 02:25 PM ET (US) I still think the plate will make about 2mph difference. In my case(s) I need it for draft, 2" less draft is a big difference crossing the flats.
pcrussell50	posted 10-26-2010 04:02 PM ET (US) Wow, am I reading a thread in the fast outboard boat forum, (whose name is not given in deference to Jim)? Because that is how a lot of this content is reading. Not saying that's a bad thing, btw. I you are really interested in squeezing the last bit of mph out of your utility/workboat, but don't want to go quite as fully committed as a low water pickup and surface-piercing prop, you might try the well known, effective-if-shadetree, best bang for the buck mod... fill in the top two holes of the water pickup. That way, if they do get uncovered by water because of zealous motor raising, they won't suck air. I don't know exactly what the water pickup scheme looks like on the ETEC, but if it looks like classic OMC/BRP motors, it's worth at least an extra inch of engine raising. I'll post a link to a great picture of exactly what I am talking about and it lools _really_ tight and professional. -Peter
Tom W Clark	posted 10-26-2010 04:38 PM ET (US) You don't need to worry about the water intakes; as the motor goes higher, the propeller will loose its grip long before the motor looses its cooling water. We are talking about a Montauk after all.
dg22	posted 10-26-2010 06:19 PM ET (US) wstr75, In your 1st post, you mentioned other performance benefits from the jack plate like less porpoising of your boat. I would consider everything, before removing.