Engine mount height

R

Roy & Dixie

New member
I read somewhere that the cavitation plate on the engine should be in line with the bottom of the boat. A search on this forum has a post re: twin 90hp Hondas and that advice is offered there.

I have a 22 CD with a single 80hp Yahama to which I have just installed a PermaTrim. When I lay a long straight edge along the bottom of the boat, with the engine tilted so PermaTrim is parallel with the boat's bottom, the PermaTrim is at least 1" below the bottom of the boat. This seems to be the original installation position.

With this boat, engine, PermaTrim combination, would I expect to experience improved performance and/or economy if I reinstalled the engine 1" higher?

If so, I read somewhere that this can be done while boat is on the trailer. The engine foot would be blocked and the tilt of the trailer cranked to remove the load of the engine off the transome. Then after loosening the 2 lower mounting bolts and removing the 2 upper bolts, the trailer tilt would be adjusted to lower the stern 1" so the 2 upper mounting bolts could be reinstalled in the next lower engine mount holes. I think it was Alex at PermaTrim that described this method.

Any input on this question and adjustment method would be appreciated.
 
Roy-

1. The raising of the engine 1" should make the boat faster and more efficient (better MPG, slightly) from less drag.

2. The method will work, or at least should work, if done with reasonable care and safety in mind.

3. If you find out that, at the new height, the engine ventilates in chop too much, you can always move it back to the original holes.

Will you have to drill any new ones? If so, be sure to A., plug the old ones properly and, B., on the new ones, clear out the sandwiched material properly and fill in with epoxy before re-drilling the new ones, now properly sealed to prevent water intrusion into the core.

If it were me, I'd try to find out who mounted the engine that low in the first place, and what intent they had in mind before I started all the above procedures. Maybe they know something that could save one the trouble of finding out the hard way ? Or maybe they were just lazy?

I'd also consider putting 1" spacer between the top of the transom and the motor mount to fill in the space that will be created when raising the engine. It's unnecessary, but I'd just feel more comfortable with the space filled in with something suitable.

Good Luck!

Joe. :teeth :thup
 
You want the Permatrim to run just on the surface of the water at planing speed. There are several factors--generally the ruler from the bottom of the boat is a good rule, but there can be variations... It may be that 1" above the transom may be better. Go up one inch and then check it running--under normal trim, with normal load in the boat.

The tilt the trailer may work, but I would feel safer with an engine hoist--they can be rented, a friend may have an "A" frame, or a good solid tree limb (has to be carefully checked) can also do the job. You do want the engine to be stable, and you want to be able to jack the tongue up enough--use more blocks and a set of hydraulic jacks if necessary to increase the range of pushing the tongue up...if you choose this method.
 
Dr Bob said this:
"The tilt the trailer may work, but I would feel safer with an engine hoist--they can be rented, a friend may have an "A" frame, or a good solid tree limb (has to be carefully checked) can also do the job. You do want the engine to be stable, and you want to be able to jack the tongue up enough--use more blocks and a set of hydraulic jacks if necessary to increase the range of pushing the tongue up...if you choose this method."
Click to expand...

That would work OR you could start with the trailer set with the transom at the elevation you want the engines to finish at by raising the trailer by jacking it up to where you want it, then stabilize the engine at that level and lower the boat and trailer, with the engines stabilized, and then do the remount.

Just my thoughts, pick your own way.

Harvey
SleepyC:moon
 
Will you have to drill any new ones? If so, be sure to A., plug the old ones properly and, B., on the new ones, clear out the sandwiched material properly and fill in with epoxy before re-drilling the new ones, now properly sealed to prevent water intrusion into the core.

I will not need to drill any new holes. The bolts would simply be run through the next level of holes in the engine. The lower bolts, when loosened, will slide within the engine mount. They would prevent the engine from tilting in any direction.

I'm not sure why it was set up as it is, but it was done in Crystal River, FL where it was purchased new.

Thanks for the other suggestions.
 
Roy,

Since I also have an F80, I'm going to go take a look to compare. My motor is tilted up right now (and I've also got the trailer tilted up so I can't lower the motor all the way at the moment), but I'll measure the distance from the underside of the bracket to the top of the transom. In other words, this is the gap that would disappear if the motor were just set on the transom and allowed to rest on the top of the transom.

Okay, back. So... there is a bit of a rounded recess on the underside of the motor yoke. From the top of the black transom cap, to the "highest" point on the rounded recess is around 1-3/4". But I wasn't able to get a very precise measurement there, so to supplement: from the top of the black transom cap to the center of the top fastener holding the motor on, is 2". That fastener is in the second hole down of four possible holes. I wonder how that compares to yours?

I also installed a Permatrim but I haven't had my boat in the water since I put it on, so I have no data that way.

Sunbeam
 
Okay, back. So... there is a bit of a rounded recess on the underside of the motor yoke. From the top of the black transom cap, to the "highest" point on the rounded recess is around 1-3/4". But I wasn't able to get a very precise measurement there, so to supplement: from the top of the black transom cap to the center of the top fastener holding the motor on, is 2". That fastener is in the second hole down of four possible holes. I wonder how that compares to yours?

I just went out and measured my F80. The engine is 3/4in above the transom and there is no filler in the space. The top pair of bolts are through the 2nd down holes in the engine and the lower pair of bolts would allow the engine to slide up 1 1/2in where they are through the transom. Thus I can raise the engine 1in by useing the 3rd pair of holes down on the engine mount. Two inch raise would require new holes for the lower bolts. I do not feel any more than 1in will be necessary. That would put the top of the PermaTrim at the same level of the bottom of the hull.

Central Fla weather was down to 34F this morning with a climb into the mid 60s, but the wind and chill factor will delay a sea trial for another day or so. I'll post my readings soon.

I replaced the surge brakes master cylinder, flushed the old discolored fluid totally out, and bled the lines. The callipers, pads and discs were all good. By jacking the wheels off the ground and spinning each one, I have "bench tested" the system. I plan to take a test drive today
 
Sunbeam":3srin48o said:
From the top of the black transom cap, to the "highest" point on the rounded recess is around 1-3/4".
Click to expand...

Roy & Dixie":3srin48o said:
I just went out and measured my F80. The engine is 3/4in above the transom and there is no filler in the space.... I do not feel any more than 1in will be necessary. That would put the top of the PermaTrim at the same level of the bottom of the hull.
Click to expand...

Hi Roy,

There is no filler in the space above the transom on mine either. From what I have seen on other boats, I think it may be customary to just leave "open air" there and not have the bracket resting on anything.

So, I don't know for sure mine is right, but it seems like it's around 1" higher than yours right now, and from what you are saying, you're going to move yours up 1" and expect that to be good. So our two engines would then be about the same height. Perhaps that means mine is about right already (I wouldn't mind that at all as I have plenty of other "boat irons" in the fire!).

Sounds like your trailer is coming along great :thup

Sunbeam
 
Sounds like your trailer is coming along great

Just test drove to test trailer brakes. For 8mi on the country road, on which I live with almost no traffic, I repeadly got up to @ 45 mph, then decelerated more and more briskly, including 1 almost panic stop. I could feel the Jeep brakes engage moments before the trailer surged fwd and the deceleration increase noticeably. As someone else stated, it stops better than without the trailer attached with the same pedal pressure. The discs were too hot to touch and are beginning to shine like you would expect.

All else the same re transom and F80, it sounds like your engine is already at height I am shooting for.
 
Do also a run with out the heavy stops and check the disc temps with an IR thermometer. We check both the discs and bearings every two hours when traveling. It just takes a second--and you don't even get your fingers dirty! Can also save a bearing. (We think that we lost a set of bearings due to dragging disc breaks, so that the regular checks can avoid that down the line.) This gives you a baseline temp.
 
I don't know if different discs or setups run differently, but here are a couple of data points from my set-up:

When I started all this I was away from home and also not experienced in trailer work, save for re-packing bearings many years ago. So I had a pro shop install Kodiak disc brakes on all four wheels, new Timken bearings, new brake hoses, and a new actuator. I put on four new tires (plus a few other non-running gear-related items).

When I pointed my nose north, I found out that things were not quite all right. Two symptoms: Terrible gas mileage and my hubs were running quite hot. I can't remember exactly, but I think they were around 175ºF. At that point in time I wasn't *sure* if that was too hot (people said discs would run "hotter" and also in the past I never had an IR thermometer), but I was worried about them so I limped into a trailer place enroute. We corrected quite a few problems that could have created heat and/or kept the brakes from releasing (sharp 90º bend in brake hose, discs dragging on hubs, castle nuts much too tight and don't even get me started on how they had the cotter pins bent back). I got back on the road and of course watched it all like a hawk. The hubs were cooler sometimes but it was inconsistent. At one point they started running up in the high 100's again and - knowing what I by-then knew - I wasn't going to assume any of the rest of it was done right either. Hence I limped into the next place....

There we found one of the sets of shoes completely worn out, crookedly (seems perhaps it was installed cockeyed and got stuck that way) from being stuck on (that wheel ran hotter), and that also all four brakes were still not releasing properly. Finally, after replacing one set of shoes, the main brake hose (seems the 90º bend may have caused a break to turn into a "flap" inside it), and the actuator (again!), I had a smoothly running system. That left precious little from the first "pro" job, but at least I could click off the miles with mental peace! I also went from 9mpg up to 12.5, which was around what I expected in the first place. Ahhhhh....

Okay, that was a long lead-up :crook , but my original point was that now all four hubs run "cool" and within ten degrees of each other. Finally! They run between 70º and around 105ºF, depending on ambient temp (and this was all at ambient temps of under 80ºF). I measure them with an IR thermometer I picked up at Radio Shack. Like you said, the van stops better towing the boat than it does without it!

Sunbeam :hot
 
Of course I was deliberately trying to heat my disc by repeately accelerating and then quickly decelerating so as to check that calipers would close against the disc and then release, and that the new master cylinder was functioning properly. I then checked that there was no drag of the pads on the disc by spinning the raised wheels. Sticking calipers are a real problem on any vehicle that is not driven regularly, as anyone in the motorhome community can attest to. A previous owner stated today that he did not think the 2006 trailer was ever used much. Today I drove 25mi each way to the St Johns River, Astor, FL so as to test CD underway. Only needed to apply brakes, lightly, 5-6 times each way, but all was good!

Original intent of this thread was questions concerning engine height. I wanted to look closely at new PermTrim underway before changing engine height by 1" up. It definently needs to be raised at least 1". More might be better, but that would require raising the lower bolts and I don't want to get into that before a trial with only a 1" raise. Tomorrow I hope to get the engine up 1".
 
Roy & Dixie":6ct5gcxg said:
Original intent of this thread was questions concerning engine height.
Click to expand...

I probably could have trimmed my saga a bit :oops: Maybe it will end up helping someone else in future though.

Roy & Dixie":6ct5gcxg said:
It definently needs to be raised at least 1". More might be better, but that would require raising the lower bolts and I don't want to get into that before a trial with only a 1" raise. Tomorrow I hope to get the engine up 1".
Click to expand...

I'll be very interested to hear how that works, as I think then it will be around where mine is (which I have not had a chance to try). When you get yours raised by 1", would you mind measuring the distance from the top of the transom cap to the center of the second-down engine mount hole? I'm just curious to compare it more precisely to mine.

Sunbeam
 
probably could have trimmed my saga a bit Maybe it will end up helping someone else in future though.

Roy & Dixie wrote:
It definently needs to be raised at least 1". More might be better, but that would require raising the lower bolts and I don't want to get into that before a trial with only a 1" raise. Tomorrow I hope to get the engine up 1".


I'll be very interested to hear how that works, as I think then it will be around where mine is (which I have not had a chance to try). When you get yours raised by 1", would you mind measuring the distance from the top of the transom cap to the center of the second-down engine mount hole? I'm just curious to compare it more precisely to mine.

You had mentioned your problems with your trailer redo by the "experts" earlier. Interesting all you went through. I did make a few calls to some local shops and several scared me off. Some did not even know the state's laws related to weight and brake requirements. This goes back to why I want to learn how to and then do it myself. My mentioning the origion of the thread is because I got off the subject a few posts earlier. Most everything I have read on this forum is helpful. Thataway's advice re an IR thermometer for example.

I'll post those measurements as soon as the engine raise is completed.
 
I'll be very interested to hear how that works, as I think then it will be around where mine is (which I have not had a chance to try). When you get yours raised by 1", would you mind measuring the distance from the top of the transom cap to the center of the second-down engine mount hole? I'm just curious to compare it more precisely to mine.

Yesterday I got 2 big jobs accomplished, and they both turned out to be a lot easier than I had feared. I'll give an update on the engine raise here. This is how I accomplished it:

1) Lowered the tongue of the trailer as far as it would go.
2) Trimmed the F80 to be very close to parallel with the angle of the transom of the CD. The trim angle would allow the weight of the engine to lean onto the transom, not pull away from it after the 2 top bolts were removed. A 6x6 timber and a 2x6 filled in the space between the ground and foot of the F80.
3) The top 2 bolt's nuts were removed and the lower 2 bolts were loosened to the point that nuts were flush with the end of the bolts.
4) My wife slowly cranked the trailer tongue up, moving the stern down. As the weight of the engine was moved to the timbers, I was able to remove the top 2 bolts by backing them out with a wrench. The threads were sealed into sealant/calking.
5) The trailer tongue was slowly raised until the next set of engine holes were moved up to align with the transom holes. I could easily fine tune the engine position to align the holes.
6) Measurement of engine height indicated another inch raise would be close to perfect. It looked like there was still space for the lower bolts to slide within the lower engine mount slots, so we raised the tongue further until the next, and final pair of upper bolt holes alligned. There was not a bit of additional space in the lower bolt mounts, but it was a perfect fit.
7) All bolts were installed and tightened.

The only thing I had to do for the engine to slide up the transom was to cut 1/4" more off the edge of the black plastic strip covering the top of the transom. The engine mount widens slightly as it is moved up.

The top 2 holes are 2 1/4" down from the top of the black plastic strip. The 2 lower holes are 8" down from the top 2 bolts. The holes through the transom must have been laid out with a template for the F80, everything was just too perfect to have been randomly drilled.

Now it's off to the river for another sea trial.
 
After yesterdays sea trail: at 3600 rpm, a speed increase of about 0.7 mph (13.4 mph, up from 12.7 mph) with engine raised 2". This is with bow riding noticeably lower with PermaTrim/engine trimmed to almost max down. I actually lost 1-3mph by trimming engine up, which raised the bow. Top of PermaTrim now rides just 1-2" below water surface at this speed.
 
Roy & Dixie":2f85gd5q said:
6) Measurement of engine height indicated another inch raise would be close to perfect. It looked like there was still space for the lower bolts to slide within the lower engine mount slots, so we raised the tongue further until the next, and final pair of upper bolt holes alligned. There was not a bit of additional space in the lower bolt mounts, but it was a perfect fit.

The top 2 holes are 2 1/4" down from the top of the black plastic strip.
Click to expand...

Very slick way to make the change! I'm going to stow that one away in my "tips to remember" file. Also sounds like it made a clear improvement.

So if I'm reading this correctly, you wanted to move the engine up around 1". However (at least on my F80) the holes are around 3/4" apart. So, since you found you could, you moved the engine up two sets of holes, or around 1-1/2"? I think now yours is higher than mine, and yet it sounds like it's an an optimum height now with the Permatrim. I guess one variable is how lightly or heavily the boat is loaded (i.e. where the stern sits vis-a-vis the static water line), but just to compare as-is and be sure I understand correctly:

When you say "the top two holes are 2-1/4" down from the top of the black plastic strip," you mean the very first hole in the engine mounting plate? (i.e. the "two holes" because there are a matching holes port and starboard). If so, you are now at 2-1/4" while mine is at 1-1/4" I guess that squares with what we said earlier when, if you had moved yours up 1" it would have been at the same level as mine (but you went more like 1-1/2" when you saw you could and since each set of holes only changes it by around 3/4").

Just to re-cap then, here is how my engine is now:

Measuring down from top of black plastic cap to center of each set of holes, for the top three holes:

1-1/4"
2"
2-3/4"

It just so happens it's the second set of holes that is used for the fasteners on my engine. And there is room in the lower slot to move it up, so I could do that at some point. Nice to know.

And then, just in case the plastic cap is not quite the same on our two boats, I measured up from the colored gelcoat "bottom" line (not the black tape stripe, but the actual gelcoat line) to the same three holes and got these measurements:
9-1/4"
10"
10-3/4"

(In other words, I ignored the fourth, or bottom, set of holes in the group of four both times, just because clearly we would not be using those.)

If you get a chance to measure/compare one more time, I would be interested in the results. I'll definitely have to check it out once I get underway. Sounds like my engine is at a better height to begin with, but may possibly benefit from an additional lift (subject to sea trial to check the current height, of course).

Thanks again,

Sunbeam
 
Roy,
Did you get a chance to run the boat faster than 3600 RPM? What was RPM at WOT? The 13.4 mph may not be the ideal speed to run the boat at. Depending on the weight, I would want to see a bit more speed at that RPM--and I wonder where you are on the "planing curve"..With the bow down that much you may not be running the boat most efficiently. At a higher speed you may find the Permatrim rides on the top of the water. Still riding 1 to 2" below the surface, and bow down,--plus loosing speed as you trim engine up, makes me think you are not at ideal cruise speed.
 
Roy,
Did you get a chance to run the boat faster than 3600 RPM? What was RPM at WOT? The 13.4 mph may not be the ideal speed to run the boat at. Depending on the weight, I would want to see a bit more speed at that RPM--and I wonder where you are on the "planing curve"..With the bow down that much you may not be running the boat most efficiently. At a higher speed you may find the Permatrim rides on the top of the water. Still riding 1 to 2" below the surface, and bow down,--plus loosing speed as you trim engine up, makes me think you are not at ideal cruise speed.

I need to run at different rpm's and record my results. Earlier I had seen close to 5500 rpm WOT, so the prop should be about right. I agree the best speed/efficiency will be at a higher rpm. I was surprised to see speed not increase with less engine trim, so I must not have been well enough up on plane.
 
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