Jackplate on a 1801?

[CobbFisherman]

Look into your prop. If you want more bow lift a 3 blade. 4 blade is more stern lifting. In the chop and following seas you want more bow lift anyhow, chop I tab down to get more of the sharp bow entry in water to help the pounding

More great info, thanks. I went from a 14.5'' 19 pitch prop to a 14.5'' 17 pitch prop of the same design/brand and only gained about 100 RPM and 1 mph. I was expecting much more out of the prop change, which is what lead me to the engine height issue. I want to get the engine height just right before trying another prop. I'll do the jack plate and get the height perfect, then re-visit the prop.

With my current height and 14'' 17p prop and a 115 E-tec I'm only getting about 5300 RPM and 33 mph at WOT. My best MPG cruise is about 4200 RPM at 26 mph. I know its a slow hull, but I'm thinking it should be doing better. I'm thinking raising the motor should help.

 

[Longislandfish]

More great info, thanks. I went from a 14.5'' 19 pitch prop to a 14.5'' 17 pitch prop of the same design/brand and only gained about 100 RPM and 1 mph. I was expecting much more out of the prop change, which is what lead me to the engine height issue. I want to get the engine height just right before trying another prop. I'll do the jack plate and get the height perfect, then re-visit the prop.

With my current height and 14'' 17p prop and a 115 E-tec I'm only getting about 5300 RPM and 33 mph at WOT. My best MPG cruise is about 4200 RPM at 26 mph. I know it’s a slow hull, but I'm thinking it should be doing better. I'm thinking raising the motor should help.

I don’t know much about Etecs other than they are faster and lighter than a F115 Yamaha fourstroke. I’m running 5800-6k rpm and 35-37mph. Planning speeds are 16-18mph 3300rpm. Cruising speed 25-28mph 4400-4600rpm.

Idk what your rev limit is on the 2 stroke. I don’t expect it to rev as high as a 4 stroke, these motors are notorious for making oil when overpropped so I adjusted that to mitigate that risk.

I know that the f115 likes to swing a smaller diameter and semi cleaver blade design, not sure about the Etec. You make need to find the right blade, more or less cup and rake. Full ear vs semi cleaver. You need a prop for a mod ver hull and 2 stroke Etec. That may be wildly different than a Yamaha 4s but I have best luck after trying 5 props with a 4 blade stainless powertec scd4 in 16p.

The boat will run like a bigger drier hull if you get tabs on it, add jack plate and fine tune your prop. I go out into the ocean in bigger seas, also I know a guy who runs 40-50 miles south of block for tuna. They are great hulls. Get your performance dialed to where you like and add tabs and a plate I bet you will wonder why you waited.

 

[Longislandfish]

I don’t know much about Etecs other than they are faster and lighter than a F115 Yamaha fourstroke. I’m running 5800-6k rpm and 35-37mph. Planning speeds are 16-18mph 3300rpm. Cruising speed 25-28mph 4400-4600rpm.

Idk what your rev limit is on the 2 stroke. I don’t expect it to rev as high as a 4 stroke, these motors are notorious for making oil when overpropped so I adjusted that to mitigate that risk.

I know that the f115 likes to swing a smaller diameter and semi cleaver blade design, not sure about the Etec. You make need to find the right blade, more or less cup and rake. Full ear vs semi cleaver. You need a prop for a mod ver hull and 2 stroke Etec. That may be wildly different than a Yamaha 4s but I have best luck after trying 5 props with a 4 blade stainless powertec scd4 in 16p.

The boat will run like a bigger drier hull if you get tabs on it, add jack plate and fine tune your prop. I go out into the ocean in bigger seas, also I know a guy who runs 40-50 miles south of block for tuna. They are great hulls. Get your performance dialed to where you like and add tabs and a plate I bet you will wonder why you waited.

Stern shot of the tabs and prop

 

[tomc585]

How many RPM and MPH did you pick up after raising the motor?

For efficiency I was just trying to reduce obvious drag and the extra 1.5" helps keep the skeg out of the water when tilted up.
Performance is difficult to express without hard data but the spray pattern is better.
I'm still running WOT 40mph @ 6,000 as I was before.

 

[CobbFisherman]

Thanks everyone! I ordered a 4'' setback jack plate and will be installing it this winter. I won't be putting the boat back in the water until spring, but I'll report back on how it rides and what my optimal height is.

 

[tomc585]

With my current height and 14'' 17p prop and a 115 E-tec I'm only getting about 5300 RPM and 33 mph at WOT.

Yeah, something is holding you back. You should be at 38-40mph all day long with that motor.
Check your lower units drive ratio. You may be running the wrong prop.

 

[Longislandfish]

For efficiency I was just trying to reduce obvious drag and the extra 1.5" helps keep the skeg out of the water when tilted up.
Performance is difficult to express without hard data but the spray pattern is better.
I'm still running WOT 40mph @ 6,000 as I was before.

The Parker dealer mounts the AC plate level with keel which is standard for the boat industry, however every hull is different and the mod vee may like more height. I still believe the motor can come up another inch without reducing water pressure or increased cavitation. The bottom line. The AC plate is buried on plane and is increasing drag and reducing the hulls optimum performance, how much that is idk but I can feel more responsiveness and a higher running hull which results in a drier ride. Rather run higher on plane but the trade off here is probably more pounding since the transom has a shallow deadrise. It’s funny the Seacraft 20 has a 7.6 beam and 16 degree deadrise and it’s so much faster and better performer. At 19.6 ft long, it’s a candidate for a bracket, however it needs raised floor, closed transom. That hull is capable of speeds over 45knts, it’ carries its beam less far forward as compared to the Parker, but its sharp entry and slightly better deadrise with strakes makes for a night and day ride. Amazing what small adjustments can do for a ride. IMO a few more degrees deadrise and a closed transom with 200hp and a raised floor this hull would be a perfect inshore, nearshore hull. Mod Vees are great, until you ride in a fast hull in heavy squared seas. I love my boat but in days where I get beat I am exhausted the next day, more deadrise and hp are an overlooked component to running in anything outside of chop. No perfect boat, I’m sure there are a million perspectives.

 

[Longislandfish]

Yeah, something is holding you back. You should be at 38-40mph all day long with that motor.
Check your lower units drive ratio. You may be running the wrong prop.

Agreed, his prop slippage is high, 5800rpm 36-38mph is 10 percent slip which is ideal for performance. He’s either too low, has a larger shaft motor for his transom or is way overpropped. What year is the Parker and what is the shaft length on the leg. Make sure it’s not a 25 inch shaft on 20 inch transom. It almost sounds like it maybe. 115 etec should be hitting 40mph or even more on this hull. The low end torque alone should be launching you out of the hole immediately

 

[CobbFisherman]

The hole shot is awesome, it'll jump up on plane and put you back in the seat. Its a 1998 1800 with a 25'' transom. Motor is a 25'' shaft with 2.25:1 gearcase. Cavitation plate is currently 1/2'' below the back of the hull keel. Motor is mounted in 2nd hole down.

When i dropped from 19 pitch to 17 pitch, i only picked up 100 RPM. I was expecting to pick up ~500 RPM. I'm thinking the motor is too low and the drag is keeping it from revving out. I'm only hitting 5300 RPM at WOT at optimal trim.

Motor is in great shape, good compression, good fuel pressure, injectors cleaned and spray tested last season, etc.

Once I get the motor raised up, I can then get pack to prop selection. If i can get it revving out to 5800 i should pick up some speed.

 

[Longislandfish]

The hole shot is awesome, it'll jump up on plane and put you back in the seat. Its a 1998 1800 with a 25'' transom. Motor is a 25'' shaft with 2.25:1 gearcase. Cavitation plate is currently 1/2'' below the back of the hull keel. Motor is mounted in 2nd hole down.

When i dropped from 19 pitch to 17 pitch, i only picked up 100 RPM. I was expecting to pick up ~500 RPM. I'm thinking the motor is too low and the drag is keeping it from revving out. I'm only hitting 5300 RPM at WOT at optimal trim.

Motor is in great shape, good compression, good fuel pressure, injectors cleaned and spray tested last season, etc.

Once I get the motor raised up, I can then get pack to prop selection. If i can get it revving out to 5800 i should pick up some speed.

Yes bring it all the way up u will gain the extra mph 35-38 you will see a difference

 

[CobbFisherman]

I installed a 4'' setback manual jack plate. I raised the engine so that the cavitation plate is 2'' above the bottom of the hull, when the plate is parallel to the hull bottom. This position is about 1/4'' higher than if the engine was mounted in the top hole. Motor was previously mounted with the cavitation plate 1/2'' below the bottom of the hull.

With the engine optimally trimmed and the boat on plane, the front of the cavitation plate is touching the water surface and the back of the plate is about 1/2'' above the surface. The water pickups on my E-tec are still well underwater and I don't have any water flow or cooling issues.

I picked up about 2 mph at every RPM when on plane and gained about 100 rpm at WOT.

At any given engine trim level (with the trim tabs fully up) the bow rides slightly higher. I don't have any porpoising. The boat rode very flat before, and it took significant engine trim to raise the bow when on plane, so I like the added bow rise.

I do not have 'smart' gauges, so I don't know real time fuel burn. I can only calculate by miles run according to chartplotter divided by gallons added when filling up. I've only burned about a half tank so far, but I think I'm getting better mileage. 2 runs to a certain fishing spot used to burn about 1/4 tank of fuel, and I'm using less than that now. I'll report back on gas mileage after I fill up.

I don't see any downsides of the 4'' setback jack plate and I'm very happy with the upgrade.

 

[Efx]

I installed a 4'' setback manual jack plate. I raised the engine so that the cavitation plate is 2'' above the bottom of the hull, when the plate is parallel to the hull bottom. This position is about 1/4'' higher than if the engine was mounted in the top hole. Motor was previously mounted with the cavitation plate 1/2'' below the bottom of the hull.

With the engine optimally trimmed and the boat on plane, the front of the cavitation plate is touching the water surface and the back of the plate is about 1/2'' above the surface. The water pickups on my E-tec are still well underwater and I don't have any water flow or cooling issues.

I picked up about 2 mph at every RPM when on plane and gained about 100 rpm at WOT.

At any given engine trim level (with the trim tabs fully up) the bow rides slightly higher. I don't have any porpoising. The boat rode very flat before, and it took significant engine trim to raise the bow when on plane, so I like the added bow rise.

I do not have 'smart' gauges, so I don't know real time fuel burn. I can only calculate by miles run according to chartplotter divided by gallons added when filling up. I've only burned about a half tank so far, but I think I'm getting better mileage. 2 runs to a certain fishing spot used to burn about 1/4 tank of fuel, and I'm using less than that now. I'll report back on gas mileage after I fill up.

I don't see any downsides of the 4'' setback jack plate and I'm very happy with the upgrade.

Nice information and write up. A well performing boat that is balanced and predictable makes all the difference.

 

[Longislandfish]

I installed a 4'' setback manual jack plate. I raised the engine so that the cavitation plate is 2'' above the bottom of the hull, when the plate is parallel to the hull bottom. This position is about 1/4'' higher than if the engine was mounted in the top hole. Motor was previously mounted with the cavitation plate 1/2'' below the bottom of the hull.

With the engine optimally trimmed and the boat on plane, the front of the cavitation plate is touching the water surface and the back of the plate is about 1/2'' above the surface. The water pickups on my E-tec are still well underwater and I don't have any water flow or cooling issues.

I picked up about 2 mph at every RPM when on plane and gained about 100 rpm at WOT.

At any given engine trim level (with the trim tabs fully up) the bow rides slightly higher. I don't have any porpoising. The boat rode very flat before, and it took significant engine trim to raise the bow when on plane, so I like the added bow rise.

I do not have 'smart' gauges, so I don't know real time fuel burn. I can only calculate by miles run according to chartplotter divided by gallons added when filling up. I've only burned about a half tank so far, but I think I'm getting better mileage. 2 runs to a certain fishing spot used to burn about 1/4 tank of fuel, and I'm using less than that now. I'll report back on gas mileage after I fill up.

I don't see any downsides of the 4'' setback jack plate and I'm very happy with the upgrade.

It sounds like what I predicted with the engine height of these hulls. I had a hunch awhile back and raised my engine up to max height and could still see my AC plate under the water on plane. The boat responded a lot better and still felt it could go higher. These aren’t designed for speed but every hull design is different and Parker went with level with the keel for a basic rigging, nothing wrong with it but after you play with props and pitches you are left with height, and I figured 2 inches from the bottom was the sweet spot. Only question is, on high speed turns do you loose traction or does the the engine blow out? It sounds like the hull can benefit from an increased height

 

[CobbFisherman]

It sounds like what I predicted with the engine height of these hulls. I had a hunch awhile back and raised my engine up to max height and could still see my AC plate under the water on plane. The boat responded a lot better and still felt it could go higher. These aren’t designed for speed but every hull design is different and Parker went with level with the keel for a basic rigging, nothing wrong with it but after you play with props and pitches you are left with height, and I figured 2 inches from the bottom was the sweet spot. Only question is, on high speed turns do you loose traction or does the the engine blow out? It sounds like the hull can benefit from an increased height

Can't say I've done much high speed sharp turning, but when cruising at 26-28 mph and making 45-60 degree turns it does fine. Tring to do a sharp 90 at 30+ might be a problem, but I never have a need to drive that way...

 

[warthog5]

I was expecting to pick up ~500 RPM.

Don't know where you got that number?

1in of pitch is usually a "Standard" of 200RPM in figuring. I have seen 150 to 200 RPM in figuring.

but after you play with props and pitches you are left with height

You have it backwards... You reset the height 1st.... Then the prop change.

Doing it as YOU said.... You would do a prop change.... $$$$ ..... Then do a height change..... Then do another prop change .... More $$$$ for another prop.

 

[CobbFisherman]

Don't know where you got that number?

1in of pitch is usually a "Standard" of 200RPM in figuring. I have seen 150 to 200 RPM in figuring.



You have it backwards... You reset the height 1st.... Then the prop change.

Doing it as YOU said.... You would do a prop change.... $$$$ ..... Then do a height change..... Then do another prop change .... More $$$$ for another prop.

I was figuring ~500 ish RPM gain from dropping 2in of pitch. I guess that was on the high side, but only gaining 100 RPM told me that something else was wrong.

After raising the motor my 14.75in diameter x 17pitch prop is right about where i want to be. I could drop another inch of pitch and pick up some more WOT RPMs, but I'm within the WOT RPM range specified in my E-tec manual and i like the slightly faster cruise with the 17 pitch. Hole shot is still awesome.

Motor height first then prop is exactly right. I wish i knew that a year ago!

Thank you to everyone who helped me get the boat dialed in!

 

[Longislandfish]

Don't know where you got that number?

1in of pitch is usually a "Standard" of 200RPM in figuring. I have seen 150 to 200 RPM in figuring.



You have it backwards... You reset the height 1st.... Then the prop change.

Doing it as YOU said.... You would do a prop change.... $$$$ ..... Then do a height change..... Then do another prop change .... More $$$$ for another prop.

You are right, but what I was referring to was if you have maxed your height on your bracket out, played with props and were curious to know if the motor could also be placed on a JP then yes. Otherwise most people don’t touch the factory set heights bc the manufacturer declared it was optimal at this position. A mod vee hull isn’t a VDH hull and it’s not designed for speed as much as it is for efficiency and stability. Reverse chines and a shallow deadrise and somewhat sharp entry there is only so much performance you can achieve with this work boat style bottom. This hull runs better with the motor jacked all way up. And he is right on the money with 2 inches above the keel.

 

[warthog5]

Otherwise most people don’t touch the factory set heights bcause the manufacturer declared it was optimal at this position

I would disagree with you... We have been discussing engine height changes here for over a decade.

Now I will speak to all boats in general... The manufacture or dealer usually has the engines to low... They don't care that your not getting max performance out of it... They also don't have to contend with "Joe 1st boat owner" not understanding that in a hard turn the engine needs trimming down. Their consern is no come back from the family wanting to take a boat ride.