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Author Topic:   Engine Height: Mechanics of Adjusting

montaukman posted 05-05-2005 10:25 AM ET (US)
Is it an easy [task] to raise and lower the engine? Can a novice person do it? Can one person do it? I am not going to mess with it until I know I have to. I am just curious as to whether is is an easy task.
I will be checking to see my engine height today. I will be installing fins so I need to be sure that the fins are in line with the water level as I an underway.
I am not sure what hole I am on. It was a factory setting for for the 170 and I have not touched it yet. I have the 90-HP Mercury four-stroker.
Thanks,
Alan
bsmotril posted 05-05-2005 02:22 PM ET (US)
I've used both Doel Fins, and the Stingray. In both cases, when the boat was trimmed for max speed at any given RPM, in calm water, the fins ran out of the water, just above the water surface. With the engine tucked in for starting, or rough water running, the fins were submerged. That way, you have minimum impact on economy, but the fin still provides the rough water and slow plane benefits with the motor trimmed in. BillS
JohnJ80 posted 05-05-2005 02:33 PM ET (US)
How you do this is experimentally.
You need to raise the engine up as high as you can get it without the prop blowing out or losing the cooling water stream. At this point, you will be at the proper height.
Most Whalers want the AV plate to be at or above 1.5" above the bottom of the hull.
J
kingfish posted 05-05-2005 03:30 PM ET (US)
Amen
John
montaukman posted 05-05-2005 03:40 PM ET (US)
Thanks for the help. But, i was more curious about how to actually raise and lower the engine. Can it be done easily or is it involved? One or two people.
I am nervous about messing with the factory settings yet I assume this is a common task and that i can always go back to the position that was setup by the factory.
Any help?
Thanks,
Alan
newt posted 05-05-2005 03:52 PM ET (US)
I think most who have tried this method will agree that it is the easiest:
1. Using your trailer tongue jack, lower the front of the trailer enough to trim your engine down with a block of wood under the skeg.
2. Clamp, strap, or otherwise secure the engine from falling over.
3. Remove the engine mounting bolts.
4. Jack trailer tongue up thereby lowering the stern until engine bracket holes line up with holes in transom at desired location.
5. Bolt engine back on.
Note: When I raised the Mercury engine on my Montauk, I had to strap the engine in place, but the Johnson motor on my Revenge has two slotted holes in the engine bracket and I just loosened those bolts which held the engine nicely.

I would recommend having a helper, but others have done it solo. All-in-all, it is a pretty easy task.
Phil Tyson posted 05-05-2005 05:08 PM ET (US)
Newt -
I assume this method works if the blind holes are not being used.
If they are being used, you may need to drill new holes and that is a whole different story.
I considered this for my Yamaha but can't tell if I would have to drill or not so have left it on the bottom of my list.
Marlin posted 05-05-2005 06:07 PM ET (US)
I used newt's technique to move the Merc 115 4-stroke on my 160 Dauntless a couple times. I backed the boat just into the garage, and looped a line over an overhead stud and tied it off to the engine hoist eyes. I also tied the engine hoist eyes off to each stern cleat. As a final precaution against the skeg slipping out, I tied it off forward to the front of the trailer.
No problems at all.
-Bob
jimh posted 05-05-2005 08:04 PM ET (US)
Alan, based on what I have come to know about you and your boating experience, formed from reading your many questions, I would not recommend you modify the engine mounting height.
The Boston Whaler company has tested and configured your boat and motor combination, and I do not think there is a great likelihood that you will be able to discover some new arrangement or setting that will improve the performance. The Boston Whaler company has been selling the 170 MONTAUK for several years, and I cannot imagine that they do this in total ignorance of potential performance improvements that could be unlocked by making simple changes like adjusting the engine mounting height.
Teak Oil posted 05-05-2005 11:08 PM ET (US)
Mercurys dont even have blind holes do they?
montaukman posted 05-06-2005 08:40 AM ET (US)
Hi Everyone,
thanks for the help on this.
Although it seems like a job i can handle, i am going to lean towards Jimh's advice and not attempt it. I actually wasn't sure if I would try. I just wanted to know how in the event that I needed to adjust it in the near future.
Jimh, you are right, it prob would have been too much for me being the novice that I am. I tend to lean towards the conservative side. Thanks for your input.
Everyoine on here has (have?) been so helpful and patient with me and i just wanted to give a global thank you to all of you.
All the best,
Alan
Binkie posted 05-08-2005 12:20 AM ET (US)
Jimh is probably right with the setup by BW, but then again if you don`t try things, you`ll never learn. Its the only way to build self confidence.
davej14 posted 05-08-2005 09:26 PM ET (US)
Alan,
If you decide to change your motor height I strongly recommend that you pay the dealer to have it done. It will only be a 30 minute job for them and they will have the proper equipment to secure the motor. Be sure to clean the old silicone off the hull and apply a fresh coating to both the hull and the mounting bolts. I found that some dealers like to apply an adhesive sealer like 3m 4200 or worse 3m 5200. DO NOT let them use anything but a high quality silicone rated for below water line use for mounting your motor. Adhesive sealers will make future changes more difficult and could result in damage to the gel coat.
Dave J.
JohnJ80 posted 05-08-2005 10:54 PM ET (US)
Geez you guys, adjusting the motor is NO BIG DEAL. You are scaring the poor guy to death about this. I'd hate to think that you are putting him off from adjusting what is probably the most critical adjustment on the whole boat for ride quality and performance.
On top of that, if you do it at the dealer - that is a royal pain since you have to keep trying it, pulling it out and taking it over to the dealer. He could have this all done and over with in about 2 hours at the boat landing.
If you are going to start doing whaler stuff, this is one of the simplest places to start.
If anyone wants detailed instructions to do this simply, just do a search on my name and Dauntless 15. I wrote out a step by step processes including the tools you need.
J.
montaukman posted 05-08-2005 11:21 PM ET (US)
Once again, thanks for the help.
I was only thinking about changing my engine height to accomodate the fins i purchased in the event that they were not at the right height to the water when running.
I was more just curious to know how to do it and whether it was a big job.
While it sounds easy enough, bottom line I feel that if I have to do it, I will bring it to the dealer. Truth be told, i think my factory settings are ok.
Thanks again for the help.
All the best,
Alan
davej14 posted 05-10-2005 07:48 PM ET (US)
Johnj80,
I checked your post. The problem is that the newer Merc's do not have slots for the bottom bolts but have individual holes. To raise one of the later vintage motors you must remove all the bolts or tilt the motor away from the transom enough to clear them. Without adequate rigging this makes motor adjustment risky. In my opinion this should not be done at the ramp, but then again, I am not a risk taker.
mhoyt01 posted 05-11-2005 06:49 PM ET (US)
I say just buy a engine hoist at harbor freight. They're like $150 when they go on sale and it's scary how often I use it.
Matt
LHG posted 05-11-2005 08:11 PM ET (US)
Look into renting an engine hoist for about $25/day.
I raise and lower engines by using the trailer method and and overhead beam(s) in the garage, using steel cable and clamps. For Mercs you need their lifting eye, which threads into the top of the flywheel. I hang the engine, and also put blocking under the skeg. Whole operation is quite easy.
Marsh posted 05-11-2005 09:04 PM ET (US)
Did mine in my garage, alone, following Newt's procedure above. VERY easy. Biggest problem was the clean up of old and new silicone seal. Messy stuff, but then, I tend to get messy anyhow. BTW, My rig is an '04 Montauk, with a 115 Merc. Re-positioned my engine to the center holes...two above, and two below, the mounting bolts.
Like Jimh said, though, I can't tell a whole lot of difference vs. original setting: one hole lower in water.
Still, it's fun to tinker, and besides, I just can't help it. I must be my nature. Lawn mowers...trucks and cars...boats...I can never leave well-enough alone. I gather I'm not alone.
Marsh
JohnJ80 posted 05-11-2005 09:45 PM ET (US)
Anyway you choose to do it of the many methods, none of them are very difficult.
Anyhow, if you are going to put a fin on your motor, then having the motor mounted at the proper place is very important. If the fin is too low it can make the whole problem worse, cause more porpoising and certainly be a lot more drag. So, if you put the fin on, you, almost invariably, will need to move the motor up from the factory set position.
Besides that, in general for most conditions, the factory position is set conservatively, that is to say, low. The factory recommends 3/4" above the lowest point of the hull. Most that have fooled with it will tell you that 1-1.5" is better.
J
The Chesapeake Explorer posted 05-12-2005 09:12 PM ET (US)
Montaukman .. Exactly at what height from the top of the transom is the center of your prop? I am about to raise my 2004 Yamaha 90 2S. I had it on the top holes. It is 29 inches from transom to centerline of the prop..too far down. My Old ERude was 27 1/2 inches. I have a engine lift so no problem , Post your prop center height and see where others are at.That should give you some idea. My boat is a classic 17 Montauk so it does not matter in reguard to your height.Different hull. Bright light in my head says to make this a topic to post to for future reference for all!
davej14 posted 05-12-2005 11:27 PM ET (US)
The only meaningful data is the position of the prop relative to the bottom of the boat. Generally this is given by the dimension from the bottom most point of the transom to the anti-cavitation plate. I think most would agree that the plate should be 3/4" to 1 1/2" above the bottom most point of the transom. Hope this helps.
aja posted 05-13-2005 10:00 AM ET (US)
I raised my '92 Johnson 150 on my OR 19II this spring and it was fairly easy to do alone in my garage. I lowered the jack (bow) and blocked both sides if the cavitation plate rather than putting the weight on the fin as it sounds like others have done.
One part of the job I hadn't expected was the black plastic trim piece which covers the "green" glass on the outboard upper edge of my transom was in a gap in the casting just above the motor transom mount. When I started raised the motor, this trim ended up getting pulled off by the weight of the motor against the boat. I had seen this coming so had removed the screws I could get at, but wanted to thank the person at the factory who chose to put two screws directly under the tilt hinges (I don't know what else to call them) so they were absolutely impossible to remove with the engine in place. Jacking the motor ended up yanking the screws out by the roots and I filled the holes with marine tex later on and cut the trim piece down to end at either side of the motor.
Another thing I didn't like about the job was sealing the outboard ends of the mounting bolts once I was putting everything back together. The motor was never more than 1/8" off the transom do I did my best to squeeze 3M 4000 into all of the gaps and on the nuts and washers. I could only do this on the outboard side of the mount since the tilt/trim mechanism blocked access to the inboard sides of the mount – some might have squeezed in around all sides of the bolts but I really doubt it. The bottom bolts go into slots on this motor which although they made the job of raising the motor very simple, are pretty much impossible to seal as I understand bedding other components (compressing the sealant around the area you are trying to seal). After pulling the old sealant out, I just globbed sealant all around where the bolt entered the transom and hoped for the best. I still can’t believe people are so concerned about sealing small screws on transducers and other hull fittings when these large through bolts at a most critical location are so badly sealed and are immersed whenever the boat is in the water. I also imagine I was much more concerned about this than many dealers installing and working with outboards every day would be.
I have had the boat out a couple of times now and it seems to run well with this new arrangement. The ventilation / cavitation plate runs right at the surface when on a plane where it would toss a rooster tail before when the engine was set too low. I’m not sure I can really feel a significant difference in performance yet but we’ll see how this arrangement works as things warm up and I can use the boat under different conditions.
JohnJ80 posted 05-15-2005 11:45 PM ET (US)
As an aside, we all talk about measuring the distance to the lowest point of the hull. In point of fact this is damn near a useless task. Where do you measure to? What angle is the AV plate supposed to be at?
Seems simple, but the geometry of the whole thing when you try to do it comes out to be pretty much useless. You are trying to position the motor within 3/4" and the error in the measurement depending on the angle of the motor etc... is more than that.
So, back to my original premise - you get to the proper setting for the way YOU use the boat by experimentation. That means you need to have a very convenient way to change the settings or you are never going to get it right. It is going to take several interations. If you have to run to the dealer and get him to do it it is going to take you a very long time. Learn how to do it at the launch, if possible, and then you can get it done in a couple of hours.
J

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Author	Topic: Engine Height: Mechanics of Adjusting
montaukman	posted 05-05-2005 10:25 AM ET (US) Is it an easy [task] to raise and lower the engine? Can a novice person do it? Can one person do it? I am not going to mess with it until I know I have to. I am just curious as to whether is is an easy task. I will be checking to see my engine height today. I will be installing fins so I need to be sure that the fins are in line with the water level as I an underway. I am not sure what hole I am on. It was a factory setting for for the 170 and I have not touched it yet. I have the 90-HP Mercury four-stroker. Thanks, Alan
bsmotril	posted 05-05-2005 02:22 PM ET (US) I've used both Doel Fins, and the Stingray. In both cases, when the boat was trimmed for max speed at any given RPM, in calm water, the fins ran out of the water, just above the water surface. With the engine tucked in for starting, or rough water running, the fins were submerged. That way, you have minimum impact on economy, but the fin still provides the rough water and slow plane benefits with the motor trimmed in. BillS
JohnJ80	posted 05-05-2005 02:33 PM ET (US) How you do this is experimentally. You need to raise the engine up as high as you can get it without the prop blowing out or losing the cooling water stream. At this point, you will be at the proper height. Most Whalers want the AV plate to be at or above 1.5" above the bottom of the hull. J
kingfish	posted 05-05-2005 03:30 PM ET (US) Amen John
montaukman	posted 05-05-2005 03:40 PM ET (US) Thanks for the help. But, i was more curious about how to actually raise and lower the engine. Can it be done easily or is it involved? One or two people. I am nervous about messing with the factory settings yet I assume this is a common task and that i can always go back to the position that was setup by the factory. Any help? Thanks, Alan
newt	posted 05-05-2005 03:52 PM ET (US) I think most who have tried this method will agree that it is the easiest: 1. Using your trailer tongue jack, lower the front of the trailer enough to trim your engine down with a block of wood under the skeg. 2. Clamp, strap, or otherwise secure the engine from falling over. 3. Remove the engine mounting bolts. 4. Jack trailer tongue up thereby lowering the stern until engine bracket holes line up with holes in transom at desired location. 5. Bolt engine back on. Note: When I raised the Mercury engine on my Montauk, I had to strap the engine in place, but the Johnson motor on my Revenge has two slotted holes in the engine bracket and I just loosened those bolts which held the engine nicely. I would recommend having a helper, but others have done it solo. All-in-all, it is a pretty easy task.
Phil Tyson	posted 05-05-2005 05:08 PM ET (US) Newt - I assume this method works if the blind holes are not being used. If they are being used, you may need to drill new holes and that is a whole different story. I considered this for my Yamaha but can't tell if I would have to drill or not so have left it on the bottom of my list.
Marlin	posted 05-05-2005 06:07 PM ET (US) I used newt's technique to move the Merc 115 4-stroke on my 160 Dauntless a couple times. I backed the boat just into the garage, and looped a line over an overhead stud and tied it off to the engine hoist eyes. I also tied the engine hoist eyes off to each stern cleat. As a final precaution against the skeg slipping out, I tied it off forward to the front of the trailer. No problems at all. -Bob
jimh	posted 05-05-2005 08:04 PM ET (US) Alan, based on what I have come to know about you and your boating experience, formed from reading your many questions, I would not recommend you modify the engine mounting height. The Boston Whaler company has tested and configured your boat and motor combination, and I do not think there is a great likelihood that you will be able to discover some new arrangement or setting that will improve the performance. The Boston Whaler company has been selling the 170 MONTAUK for several years, and I cannot imagine that they do this in total ignorance of potential performance improvements that could be unlocked by making simple changes like adjusting the engine mounting height.
Teak Oil	posted 05-05-2005 11:08 PM ET (US) Mercurys dont even have blind holes do they?
montaukman	posted 05-06-2005 08:40 AM ET (US) Hi Everyone, thanks for the help on this. Although it seems like a job i can handle, i am going to lean towards Jimh's advice and not attempt it. I actually wasn't sure if I would try. I just wanted to know how in the event that I needed to adjust it in the near future. Jimh, you are right, it prob would have been too much for me being the novice that I am. I tend to lean towards the conservative side. Thanks for your input. Everyoine on here has (have?) been so helpful and patient with me and i just wanted to give a global thank you to all of you. All the best, Alan
Binkie	posted 05-08-2005 12:20 AM ET (US) Jimh is probably right with the setup by BW, but then again if you don`t try things, you`ll never learn. Its the only way to build self confidence.
davej14	posted 05-08-2005 09:26 PM ET (US) Alan, If you decide to change your motor height I strongly recommend that you pay the dealer to have it done. It will only be a 30 minute job for them and they will have the proper equipment to secure the motor. Be sure to clean the old silicone off the hull and apply a fresh coating to both the hull and the mounting bolts. I found that some dealers like to apply an adhesive sealer like 3m 4200 or worse 3m 5200. DO NOT let them use anything but a high quality silicone rated for below water line use for mounting your motor. Adhesive sealers will make future changes more difficult and could result in damage to the gel coat. Dave J.
JohnJ80	posted 05-08-2005 10:54 PM ET (US) Geez you guys, adjusting the motor is NO BIG DEAL. You are scaring the poor guy to death about this. I'd hate to think that you are putting him off from adjusting what is probably the most critical adjustment on the whole boat for ride quality and performance. On top of that, if you do it at the dealer - that is a royal pain since you have to keep trying it, pulling it out and taking it over to the dealer. He could have this all done and over with in about 2 hours at the boat landing. If you are going to start doing whaler stuff, this is one of the simplest places to start. If anyone wants detailed instructions to do this simply, just do a search on my name and Dauntless 15. I wrote out a step by step processes including the tools you need. J.
montaukman	posted 05-08-2005 11:21 PM ET (US) Once again, thanks for the help. I was only thinking about changing my engine height to accomodate the fins i purchased in the event that they were not at the right height to the water when running. I was more just curious to know how to do it and whether it was a big job. While it sounds easy enough, bottom line I feel that if I have to do it, I will bring it to the dealer. Truth be told, i think my factory settings are ok. Thanks again for the help. All the best, Alan
davej14	posted 05-10-2005 07:48 PM ET (US) Johnj80, I checked your post. The problem is that the newer Merc's do not have slots for the bottom bolts but have individual holes. To raise one of the later vintage motors you must remove all the bolts or tilt the motor away from the transom enough to clear them. Without adequate rigging this makes motor adjustment risky. In my opinion this should not be done at the ramp, but then again, I am not a risk taker.
mhoyt01	posted 05-11-2005 06:49 PM ET (US) I say just buy a engine hoist at harbor freight. They're like $150 when they go on sale and it's scary how often I use it. Matt
LHG	posted 05-11-2005 08:11 PM ET (US) Look into renting an engine hoist for about $25/day. I raise and lower engines by using the trailer method and and overhead beam(s) in the garage, using steel cable and clamps. For Mercs you need their lifting eye, which threads into the top of the flywheel. I hang the engine, and also put blocking under the skeg. Whole operation is quite easy.
Marsh	posted 05-11-2005 09:04 PM ET (US) Did mine in my garage, alone, following Newt's procedure above. VERY easy. Biggest problem was the clean up of old and new silicone seal. Messy stuff, but then, I tend to get messy anyhow. BTW, My rig is an '04 Montauk, with a 115 Merc. Re-positioned my engine to the center holes...two above, and two below, the mounting bolts. Like Jimh said, though, I can't tell a whole lot of difference vs. original setting: one hole lower in water. Still, it's fun to tinker, and besides, I just can't help it. I must be my nature. Lawn mowers...trucks and cars...boats...I can never leave well-enough alone. I gather I'm not alone. Marsh
JohnJ80	posted 05-11-2005 09:45 PM ET (US) Anyway you choose to do it of the many methods, none of them are very difficult. Anyhow, if you are going to put a fin on your motor, then having the motor mounted at the proper place is very important. If the fin is too low it can make the whole problem worse, cause more porpoising and certainly be a lot more drag. So, if you put the fin on, you, almost invariably, will need to move the motor up from the factory set position. Besides that, in general for most conditions, the factory position is set conservatively, that is to say, low. The factory recommends 3/4" above the lowest point of the hull. Most that have fooled with it will tell you that 1-1.5" is better. J
The Chesapeake Explorer	posted 05-12-2005 09:12 PM ET (US) Montaukman .. Exactly at what height from the top of the transom is the center of your prop? I am about to raise my 2004 Yamaha 90 2S. I had it on the top holes. It is 29 inches from transom to centerline of the prop..too far down. My Old ERude was 27 1/2 inches. I have a engine lift so no problem , Post your prop center height and see where others are at.That should give you some idea. My boat is a classic 17 Montauk so it does not matter in reguard to your height.Different hull. Bright light in my head says to make this a topic to post to for future reference for all!
davej14	posted 05-12-2005 11:27 PM ET (US) The only meaningful data is the position of the prop relative to the bottom of the boat. Generally this is given by the dimension from the bottom most point of the transom to the anti-cavitation plate. I think most would agree that the plate should be 3/4" to 1 1/2" above the bottom most point of the transom. Hope this helps.
aja	posted 05-13-2005 10:00 AM ET (US) I raised my '92 Johnson 150 on my OR 19II this spring and it was fairly easy to do alone in my garage. I lowered the jack (bow) and blocked both sides if the cavitation plate rather than putting the weight on the fin as it sounds like others have done. One part of the job I hadn't expected was the black plastic trim piece which covers the "green" glass on the outboard upper edge of my transom was in a gap in the casting just above the motor transom mount. When I started raised the motor, this trim ended up getting pulled off by the weight of the motor against the boat. I had seen this coming so had removed the screws I could get at, but wanted to thank the person at the factory who chose to put two screws directly under the tilt hinges (I don't know what else to call them) so they were absolutely impossible to remove with the engine in place. Jacking the motor ended up yanking the screws out by the roots and I filled the holes with marine tex later on and cut the trim piece down to end at either side of the motor. Another thing I didn't like about the job was sealing the outboard ends of the mounting bolts once I was putting everything back together. The motor was never more than 1/8" off the transom do I did my best to squeeze 3M 4000 into all of the gaps and on the nuts and washers. I could only do this on the outboard side of the mount since the tilt/trim mechanism blocked access to the inboard sides of the mount – some might have squeezed in around all sides of the bolts but I really doubt it. The bottom bolts go into slots on this motor which although they made the job of raising the motor very simple, are pretty much impossible to seal as I understand bedding other components (compressing the sealant around the area you are trying to seal). After pulling the old sealant out, I just globbed sealant all around where the bolt entered the transom and hoped for the best. I still can’t believe people are so concerned about sealing small screws on transducers and other hull fittings when these large through bolts at a most critical location are so badly sealed and are immersed whenever the boat is in the water. I also imagine I was much more concerned about this than many dealers installing and working with outboards every day would be. I have had the boat out a couple of times now and it seems to run well with this new arrangement. The ventilation / cavitation plate runs right at the surface when on a plane where it would toss a rooster tail before when the engine was set too low. I’m not sure I can really feel a significant difference in performance yet but we’ll see how this arrangement works as things warm up and I can use the boat under different conditions.
JohnJ80	posted 05-15-2005 11:45 PM ET (US) As an aside, we all talk about measuring the distance to the lowest point of the hull. In point of fact this is damn near a useless task. Where do you measure to? What angle is the AV plate supposed to be at? Seems simple, but the geometry of the whole thing when you try to do it comes out to be pretty much useless. You are trying to position the motor within 3/4" and the error in the measurement depending on the angle of the motor etc... is more than that. So, back to my original premise - you get to the proper setting for the way YOU use the boat by experimentation. That means you need to have a very convenient way to change the settings or you are never going to get it right. It is going to take several interations. If you have to run to the dealer and get him to do it it is going to take you a very long time. Learn how to do it at the launch, if possible, and then you can get it done in a couple of hours. J