Need help w/ new motor setup

[MikeEiden]

I had a new 115 Mercury EFI 4-stroke put on my 17 Tracker Targa WT today and need some advice on getting some of the quirks out of the current setup. This may get lengthy but bare with me.

Ok, first time right out of the dealer the motor is set on the top mounting hole which was the same as my old motor. The cav plate is about the right height with the bottom of the boat. The prop was one recommended by the shop and was a 17 pitch Trophy 4-blade SS. My experience was horrible torque steer (no anti-feedback helm) I experienced bad porpoising from mid-range to WOT. Even trimmed all the way in and yes I checked how far it would trim in, it took a while to correct. I also get a fair amount of bow rise when taking off. So back to the dealer I went.

Next we put back on my old 19 pitch 3 blade Hustler prop. Tried it on Swan tonight and fortunately the torque steer was gone and even less porpoising. Now I get the porpoising only in the mid-range/cruise speed. If I run 4000rpm at 26-28mph it will start bouncing. It also gets severe if I turn semi-sharply. I still get a fair amount of bow rise on take off until the rpms get up there.

The new motor is about 75lbs heavier than my previous motor so there was some weight added to the transom. Never had porpoising issue with my previous motor. Any info or experiences and how you fixed them would be helpful. I will continue to work with the shop but with shift work I don't get a lot of days to try things out.

Thanks in advance,

Mike

[marine_man]

Just so I'm completely clear.. you're experiencing porposing problems even when you have the motor trimmed down all the way?

What are you seeing for RPM's at WOT?

marine_man

[MikeEiden]

In a sense I still see it when trimmed in all the way. As of right now I really can't trim out much more than 1/4 or the prop starts to slip. The previous 4 blade I could go out 1/2 before noticing it. Well once I notice it begins to bounce I trim in and it lessens it but doesn't make it go away. I have to change speeds so either slowing down off plane or punching it full throttle, still trimmed in, will usually get it to stop.

It's that mid-range that seems to be the most problems now. The 4 blade would do it at WOT which was pretty scary, really.

It must be the Tracker hull because I've never been able to trim out much so I wasn't to suprised. But I feel like I can't take full advantage when I have to stay 1/4 or less. I run 6000rpm at WOT with this prop and 6100 with the 4 blade.

I'm going out to Swan in a little bit and move some weight around just to see if that helps. Also try not to find a choppy part of the lake.

[CAMAN]

It may be a good investment installing a jackplate and playing with the height. To me it sounds like the motor is a little high and on the edge of cavitation. The jackplate will also move the motor back a few inches and that should help too.

[marine_man]

I would suggest checking your cavitation plate vs the bottom of the hull... how close is pretty close?

Does your Tracker have a 25" Transom? Did they put a 25" motor on the back too?

Based on what you're describing I'm really surprised you're having these issues...

marine_man

[MikeEiden]

I ran the boat for a while again today trying different things. First I just ran it as is since there was less chop and I can get a feel for it more. The boat didn't porpoise unless I trimmed up to far for the speed I was running. Again I couldn't really go past 1/4 at all unless at WOT. Bounce was most evident at ~4000rpms and running 25-26mph. Just increasing throttle to 4600-4800 would jump me up to 33mph range. When at this speed and trimmed to 1/4 if I punch it the prop spins out some. I have to trim in below 1/4 to do this. Even throttle increase wouldn't spin it out.

So far it seems very trim sensitive. I can barely touch the button either up or down depending on speeds and hear it either grab more (and watch the speed go up and rpms down some) or it starts to slip.

Like you said Caman it almost seems like I'm on the verge of cavitation. I'll look more into jackplates and see if that's a route to go. I've read on them some before but never tried. I was so underpowered before my old motor never spun out nor caused porpoise. It's sweet spot was 1/4 but much past it just seemed to over load it and loose hold.

This may end up being an expensive and time consuming process. I'm not looking to run 50mph or anything but the ride and drive-ability can use some help.

Please keep the suggestions coming.

[TR21HP]

I agree with the above posters. That motor is setup too high. Do you have a water pressure gauge on your dash and if you do what are you running? You should be able to fully trim that motor at wide open throttle with no porpoising and if are experiencing prop spin that tells me you need to get a jackplate on that and get it setback and lowered.

[marine_man]

I'll look more into jackplates and see if that's a route to go. I've read on them some before but never tried. I was so underpowered before my old motor never spun out nor caused porpoise. It's sweet spot was 1/4 but much past it just seemed to over load it and loose hold.

Be sure to read my post just above your last post Mike... looks like we may have started them at the same time.

A Jackplate may take care of it; but you don't typically see jackplates on aluminum boats, nor are they typically needed and I can't hardly believe required in this case, unless you boat has a very bad hook in it or something to that effect.

marine_man

[CRFan1]

I will be curious to see how this gets resolved because I have noticed that my new Alumacraft 165 CS will start to porpoise whether at cruise or full throttle if I trim to much. I was assuming that is kinda normal (especially on a relatively small boat like mine) but maybe not?

[TR21HP]

CRFan1, You are right in that if you overtrim any boat it will usually porpoise. It is just seat time with the boat to see where that is. Marine man brought up an interesting point in that the Tracker could have a hook in the hull which could cause this. I remember reading on another site where there is aremedy for that but I can't remember what it was.

[CRFan1]

CRFan1, You are right in that if you overtrim any boat it will usually porpoise. It is just seat time with the boat to see where that is. Marine man brought up an interesting point in that the Tracker could have a hook in the hull which could cause this. I remember reading on another site where there is aremedy for that but I can't remember what it was.

Ok thanks for the info and I kind of figured. Every time out I kinda have been experimenting with trimming and such but I am at 4-5 hours on this boat so I am still getting to know her, hehe. I certainly hope the original poster in this thread can find a resolution to his problem!

[hydro]

Guys, a "hook" in the bottom of the hull will do just the opposite of the symptom-it will push the bow down and stick the boat to the water. Since the boat did not porpoise with the old motor, I would not suspect the hull has changed. Another tidbit in the original post is the mention of excessive torque steer, which can be caused by running the prop too deep, or way too high "paddlewheeling" the bottom blades. Too get the prop high enough to do that will run stock water intakes dry and other problems will pop up.

MikeEiden, Can you take a picture in the driveway? Trim the motor all the way in, have a helper place a straightedge at the bottom of the hull out past the prop. Post the picture here. That will identify the mounting height of the motor, the cavitation plate location, and the angle of the propshaft relative to the bottom of the boat. We can take a shot at the problem with that information.

[MikeEiden]

I'll do that Hydro. I have to find a spot where I can get the motor all the way down. I lowered as much as possible and it looks like it may be a little high to me but hard to tell for sure. I talked to the dealer today and they said it seemed a little high but figured it was the design of the hull. They pretty much said there isn't much I can do and this is about as good as it gets. They also said a jackplate would be going backwards for the problem and not recommended. No explaination on it.

Hydro, I only noticed torque steer when using that 4 blade SS prop. The 3 blade has relatively no torque at the wheel now.

My previous motor never porpoised even when I trimmed it way out. Mainly because when I got to high the prop would spin out.

Here's another question for ya guys with the 4-stroke. When you hit the trim button does your motor hesitate? I touch the button and the motor almost stops.

Unfortunately I'm working nights tonight so I'll get a pick taken and posted asap.

Marine-man. I checked to make sure it is a 20" transom and 20" motor and everything checked out.

All in all today the motor ran fine. I'm getting used to the idea that the thing is a little weak out of the hole. But it stinks I have to run about 4800rpms or more to have a decent ride. Plus it's no fun to sit and play with the trim everytime the conditions change ever so slightly.

[hydro]

Here's what the picture should show, for the sake of arguement.

This shows the relative position of the gearcase, cavitation plate, and prop for a typical aluminum fishing rig. The "water plume" is how the water rebounds once it leaves the hull surface. Notice that with the cavitation plate at trhe bottom of the hull, it actually runs submerged in the water plume and creates leverage, either positive or negative depending on trim setting. That may be part of the problem. To some extent, raising the motor may cure that problem, but it may also make it worse. Porpoising is caused by the motor trying to push the bow up, then losing leverage. It is usually directly related to trim angle. If the prop blows out as the boat's nose drops, I would try lowering the motor and trying it again.

The jackplate idea would allow you to play with motor height, but I suspect the added weight of the 4 stroke is already part of the problem. A jackplate would put that weight farther out back, increasing the leverage that it exerts on the boat and may make the problem worse. Jackplates are typically employed to increase the leverage applied by the prop, with the intent of keeping the bow up out of the water to increase top end speed and shorten holeshot distance. (see avatar pic)

[Surface Tension]

Could be as simple as weight distribution. Get some weight off the stern and into the bow.

[hydro]

According to Tracker's HSOforum that boat can hold 29 gallons of gas. How much is in there now? Where is the tank? That can add up to a lot of ballast in a wide 18' boat.

[CRFan1]

Here's what the picture should show, for the sake of arguement.

This shows the relative position of the gearcase, cavitation plate, and prop for a typical aluminum fishing rig. The "water plume" is how the water rebounds once it leaves the hull surface. Notice that with the cavitation plate at trhe bottom of the hull, it actually runs submerged in the water plume and creates leverage, either positive or negative depending on trim setting. That may be part of the problem. To some extent, raising the motor may cure that problem, but it may also make it worse. Porpoising is caused by the motor trying to push the bow up, then losing leverage. It is usually directly related to trim angle. If the prop blows out as the boat's nose drops, I would try lowering the motor and trying it again.

The jackplate idea would allow you to play with motor height, but I suspect the added weight of the 4 stroke is already part of the problem. A jackplate would put that weight farther out back, increasing the leverage that it exerts on the boat and may make the problem worse. Jackplates are typically employed to increase the leverage applied by the prop, with the intent of keeping the bow up out of the water to increase top end speed and shorten holeshot distance. (see avatar pic)

Based on that picture...what are the affects of the motor being too low? My anti-cavitation plate is about an inch below the hull and I am just curious

[MikeEiden]

I spent time moving batteries around today to see how weight would affect it. I have a hard time believing that the ~70 extra pounds in the outboard change threw it into that much of a funk. I didn't count it out but really had a hard time believing it. Like mentioned there is a large gas tank in back that varies in weight, livewell, and passangers. I know there is a lot of weight in back at times but never affected it before (except for more struggle to get on plane). So I took 2 Gr27 TM batteries and moved them towards the front casting deck. That didn't really change things unfortunately. The tank is 3/4 full and started around full (not a very accurate gauge really).

I still don't know how it will do with the whole family in there. I'm going to play around some and get the info out you guys requested. If I can't really correct all of it I may have to invest in some trim tabs. I thought about trying these before I bought the new outboard. Heard many good things about Smart Tabs.

[hydro]

CRFan, Running the motor too low has different effects at various speeds. It increases drag at all speeds, slowing the boat down. At higher speeds it can create torque steer conditions. As a general rule, you want to run the motor as high as possible without running into "blow out" on hole shot and high speed turns. You will notice both of these effects more with the motor trimmed up so that's a good way to check the setup.

[CRFan1]

CRFan, Running the motor too low has different effects at various speeds. It increases drag at all speeds, slowing the boat down. At higher speeds it can create torque steer conditions. As a general rule, you want to run the motor as high as possible without running into "blow out" on hole shot and high speed turns. You will notice both of these effects more with the motor trimmed up so that's a good way to check the setup.

Ok thanks for the info. I don't have any torque steer issues but is seems I should be able to do better on the top end. I went from a 10.38 x13 aluminum that pulled 6K on the tach (and topped out at 30) but had way too much slip to a 10.5 x13 SS Michigan Wheel Apollo prop and the whole shot is way better and I can cruise 500 RPM less. I also picked up about 2 mph but with 3 guys in the boat it pulls about 5400 RPM, which is just a hair out of wot recommended range (5500-6000). I think I have the right prop but I may need to move the motor up in hopes of a bit more RPM?

This is a 60hp merc 4 stroke on an alumacraft classic 165 CS..both 2010.

Sorry to jump on this thread and I am following with great interest...

[hydro]

CRFan1, You are already pretty close so moving the motor up may be all you need. I would give it a try and watch to see if the WOT rpm changes. Be sure to run the trim/turn test to watch for blow out.

My current boat, a 20' fish and ski with a 200 EFI Merc picked up 10 mph just by tuning the height of the motor (with the same 14" X 23" Tempest Plus). When I bought the boat the motor was way too low, it torque steered bad, and had trouble getting out of the hole. I have a manual jackplate so that made it easy to change, but the potential is the same for you. Good luck!

[CRFan1]

CRFan1, You are already pretty close so moving the motor up may be all you need. I would give it a try and watch to see if the WOT rpm changes. Be sure to run the trim/turn test to watch for blow out.

My current boat, a 20' fish and ski with a 200 EFI Merc picked up 10 mph just by tuning the height of the motor (with the same 14" X 23" Tempest Plus). When I bought the boat the motor was way too low, it torque steered bad, and had trouble getting out of the hole. I have a manual jackplate so that made it easy to change, but the potential is the same for you. Good luck!

Thanks Hydro

[MikeEiden]

Sorry but no pics yet. Getting ready to head into work for nights again. I took the wife out and 2 boys on Trout Lake for a little bit. First time the wife has been in the boat with the new motor. Man, the addition of people really dogged the hole shot. It was even more disappointing than I could have expected. Even the wife said once we get on plane you can notice its much faster but the bow raise and time it took she said was pretty sad. It also did a little bouncing for her at cruise speed which she didn't like. But I'm learning how to run this motor already. To bad it has to be trimmed in so much at cruise to keep it from wanting to bounce. I called the marine shop from the lake and asked what options I have. They think re-prop'ing it again would help and really make a difference. Its just so sluggish out of the hole I can't see going from a 19 to a 17 pitch prop will turn things around. The 4 blade 17 pitch wasn't impressive at all.

I did ask if that doesn't work out what other option do I have. He said they could order an Optimax but there is such a shortage that I will have to wait all summer to get it. Didn't hear that when I first mentioned I was interested in the Opti's. I was told they had an order coming in but nothing about being months out.

It hasn't taken long for my excitement to turn into regret on this choice. I'll try their prop suggestions but I have my doubts.

We'll see what happens from here.

[boatfixer]

A 4 blade in your case is compounding your problem. 4 and 5 blade props provide stern lift. You need a prop with more rake as that will provide you with more bow lift. I will find out if Opti's are really back oredered or not.

[delcecchi]

I am having a hard time understanding how a motor can influence porpoising, other than by its weight and trim/mounting height. I would think that the weight distribution in the boat would make a bigger difference. I know I can tell when the front livewell is full.