Motor height - Merc 150 seapro
- Thread starter Macdeep
- Start date
Macdeep
Active Member
Ya, I mean with the previous power (115 4s), I would use my trim tabs at full nose down to get out of the hole, then back them off completely, trim out the outboard and then if necessary touch them a little bit to level the boat, but never had to used them to keep the nose down.
So really I only used the trim tabs for launch, and leveling left to right, never to keep the nose down. I had plenty of fore/aft trim control from the outboard (which had a foil, and needed a foil as it was underpowered).
Now I dont need full tabs for launch, but I use them any way because it gets me level much much faster, and it's my old habit. But with this new set up, once on plane, I need the trim tabs at about half way down (they create some spray) and I cannot release the motor trim at all or I get porpoising.
The porpoising/inability to trim out the outboard at a medium cruise speed is really the issue I'm trying to fight now. The spray issues have subsided considerably since I moved the transducer and added the bow weight/ redistributed my gear to the cuddy lockers rather than under the seats.
But that's for normal cruising speed up to ~25knots and up to 4000rpm. In all cases, whether before I had weight in the bow or not, or whether I had the foil on or not, if I kicked the speed up to 30 knots or higher, this all changes. But I have to say, I don't want to be cruising at 30-35 knots at 4500-5300 RPM. Once I get going that fast, I can release the trim tabs and back them off all the way. And I can trim out the outboard without getting porpoising. Also, no caviatation when going into a tight turn at 30 knots, same as when I go into a tight turn at 20 knots.
So I guess I just have to avoid the medium speed and only travel and high speed? But I'd really rather not. I like 22-26knots and staying under 4000 RPM for noise on deck, fuel burn, safety/reaction time, comfort in light chop etc etc.
For the poster a few back, here's my numbers again.
Prop: Solas Rubex 15.3x19 3Plus 9511-153-19
Outboard: 2025 Merc Seapro 150 (2.08 gear ratio, 4.75" case)
WOT range: 4800-5300
Boat: 18ft Malibu 182 (Cuddy with similar design to the DE185) Max HP hull rating is 175. It's definitely an butt heavy boat with a rounded bottom from the mid point back.
Performance numbers with really any load I've tried so far
3500 - 23mph 20 knots
4000 - 29mph 25-26 knots
4500 - 35mph 30 knots
5200 - 40mph 35knots - This is WOT for this prop and setup with both a 2 passenger medium load full fuel and a 4 passenger load with bow locker ~60 pounts of ballast and all other heavy stuff in the cuddy lockers. I got it to 5300 once under perfect glass conditions and about 20-30 seconds of getting the trim perfect and watching the needle slowly creeping up from 5000. As mentioned, once over 4500RPM I can release the trim tabs and start to trim out the outboard.
No, I don't have an pictures of the spray, cav plate etc when at top speed.
And I wouldn't disagree that I'd get better performance with a different prop. I was offered this prop to test since it's used and at a reasonable price from a prop shop. I think it's well suited for the RPM WOT spec, but I definitely would be interested in a second prop and keep this one as a spare tire, especially if there's some optimizing for stern lift and performance, especially if I raise the motor one last hole to get the cav plate clear of the waterline.
Correct me if I'm wrong, but it seems like to combat the porpoising I need to add more weight to the bow before I go raising the motor another notch, probably go extreme and try another 100lb on top of what I already have there.
I don't think I'll ever enjoy seeing a porpoise again
brutus
Well-Known Member
I don’t know but 300lbs of weight in the bow on a 18 ft boat seems like a lot . I’ve notice when swap from my Honda to Suzuki 225 to 300, no weight difference, but the suke swings a way bigger prop, my trim range on the suke is way smaller haven’t tried different props, just water grip , started at 21.5 then 19 then 17 pitch, now I am in low end of rpm range,it did bounced a bit( prop pushing the stern down) so moved a bit of weight to the front 100lbs max . I only use my trim tabs to level the boat side to side. To keep your cruising speed where you want it you might have to compensate with your tabs, you will loose efficiency but at least you won’t bounce around. Good luckYa, I mean with the previous power (115 4s), I would use my trim tabs at full nose down to get out of the hole, then back them off completely, trim out the outboard and then if necessary touch them a little bit to level the boat, but never had to used them to keep the nose down.
So really I only used the trim tabs for launch, and leveling left to right, never to keep the nose down. I had plenty of fore/aft trim control from the outboard (which had a foil, and needed a foil as it was underpowered).
Now I dont need full tabs for launch, but I use them any way because it gets me level much much faster, and it's my old habit. But with this new set up, once on plane, I need the trim tabs at about half way down (they create some spray) and I cannot release the motor trim at all or I get porpoising.
The porpoising/inability to trim out the outboard at a medium cruise speed is really the issue I'm trying to fight now. The spray issues have subsided considerably since I moved the transducer and added the bow weight/ redistributed my gear to the cuddy lockers rather than under the seats.
But that's for normal cruising speed up to ~25knots and up to 4000rpm. In all cases, whether before I had weight in the bow or not, or whether I had the foil on or not, if I kicked the speed up to 30 knots or higher, this all changes. But I have to say, I don't want to be cruising at 30-35 knots at 4500-5300 RPM. Once I get going that fast, I can release the trim tabs and back them off all the way. And I can trim out the outboard without getting porpoising. Also, no caviatation when going into a tight turn at 30 knots, same as when I go into a tight turn at 20 knots.
So I guess I just have to avoid the medium speed and only travel and high speed? But I'd really rather not. I like 22-26knots and staying under 4000 RPM for noise on deck, fuel burn, safety/reaction time, comfort in light chop etc etc.
For the poster a few back, here's my numbers again.
Prop: Solas Rubex 15.3x19 3Plus 9511-153-19
Outboard: 2025 Merc Seapro 150 (2.08 gear ratio, 4.75" case)
WOT range: 4800-5300
Boat: 18ft Malibu 182 (Cuddy with similar design to the DE185) Max HP hull rating is 175. It's definitely an butt heavy boat with a rounded bottom from the mid point back.
Performance numbers with really any load I've tried so far
3500 - 23mph 20 knots
4000 - 29mph 25-26 knots
4500 - 35mph 30 knots
5200 - 40mph 35knots - This is WOT for this prop and setup with both a 2 passenger medium load full fuel and a 4 passenger load with bow locker ~60 pounts of ballast and all other heavy stuff in the cuddy lockers. I got it to 5300 once under perfect glass conditions and about 20-30 seconds of getting the trim perfect and watching the needle slowly creeping up from 5000. As mentioned, once over 4500RPM I can release the trim tabs and start to trim out the outboard.
No, I don't have an pictures of the spray, cav plate etc when at top speed.
And I wouldn't disagree that I'd get better performance with a different prop. I was offered this prop to test since it's used and at a reasonable price from a prop shop. I think it's well suited for the RPM WOT spec, but I definitely would be interested in a second prop and keep this one as a spare tire, especially if there's some optimizing for stern lift and performance, especially if I raise the motor one last hole to get the cav plate clear of the waterline.
Correct me if I'm wrong, but it seems like to combat the porpoising I need to add more weight to the bow before I go raising the motor another notch, probably go extreme and try another 100lb on top of what I already have there.
I don't think I'll ever enjoy seeing a porpoise again
SpringVelocity
Crew Member
There is only one other thing can be throwing things off. I know a couple of guys with my boat had the waterlogged floor/foam thing happen. This was notorious for double eagles.
Have you ever checked?
It seems like you have some weight back there screwing things up. Not saying you have it but it might be worth checking so not your not chasing a ghost so to speak.
Have you ever checked?
It seems like you have some weight back there screwing things up. Not saying you have it but it might be worth checking so not your not chasing a ghost so to speak.
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salmonkiller01
Well-Known Member
Where are you located?
Macdeep
Active Member
Ya never checked and not sure how to. I have a scope on a wire that I can attack to my phone and was going to see what things look like through the transom and back hatches. Probably a bit of accumulated sand etc from shoes/boots as well as other gunk, but not sure if Ill be able to see any foam etc.
Otherwise, salmonkiller01, I'm in Port Mcneill.
Fisher Down
Active Member
OK, I gotta chime in after reading 2 pages at https://sportfishingbc.com/threads/prop-advice-for-merc-efi-115-on-malibu-182.93830/ and all 5 pages here.
Although there are no provincial hwy scales north of Parksville, by asking around, you should be able to find some commercial scales to weight your trailer (both unloaded and with your boat loaded) in the McNeill/Hardy/Alice/Campbell River area to get your weight figured out.
As many others have noted, you've got to verify what you're working with before you start throwing 'magic' propellors at it (weight, motor height, balance, trim angles (motor trim & tabs), verified/expected performance specs, ...). BTW, I agree that SS is the only way to go.
- Did you every verify your tach accuracy?
- Were you able to test your 115 props on this 150?
- Are the speeds you talk about knots or MPH?
- Are Malibu 182's known to be stern-heavy (I can't find any info)?
- Do (all) other Malibu 182's need to run with the PTT full in, trim tabs in use, and a hydrofoil?
- Can you speak with any other Malibu 182 owners?
- Are you able to contact any dealers who sold the Malibu 182's (other members might remember who sold Malibu)?
- How does your 182 performance specs compare to factory podded models?
Just my $0.02 worth, and GOOD LUCK.
FD
Although there are no provincial hwy scales north of Parksville, by asking around, you should be able to find some commercial scales to weight your trailer (both unloaded and with your boat loaded) in the McNeill/Hardy/Alice/Campbell River area to get your weight figured out.
As many others have noted, you've got to verify what you're working with before you start throwing 'magic' propellors at it (weight, motor height, balance, trim angles (motor trim & tabs), verified/expected performance specs, ...). BTW, I agree that SS is the only way to go.
- Did you every verify your tach accuracy?
- Were you able to test your 115 props on this 150?
- Are the speeds you talk about knots or MPH?
- Are Malibu 182's known to be stern-heavy (I can't find any info)?
- Do (all) other Malibu 182's need to run with the PTT full in, trim tabs in use, and a hydrofoil?
- Can you speak with any other Malibu 182 owners?
- Are you able to contact any dealers who sold the Malibu 182's (other members might remember who sold Malibu)?
- How does your 182 performance specs compare to factory podded models?
Just my $0.02 worth, and GOOD LUCK.
FD
Macdeep
Active Member
Wow, quite the reading mission you went on - appreciated!
I have weighed the boat on the trailer before at the dump (1750kg or 3850lb total), but I have no idea what the boat weighs on it's own - I guess I could do that. Best guess is its around 3000lb.
Tach should be accurate - replaced a few years ago and seems very reasonable across two outboards now.
I did not test any 115 props on the 150 - different gear case size. They fit but looked silly.
Speeds as posted have their units described, but here they are again:
WOT range for the seapro 150 is 4800-5300 (please dont ask or question it - I'm getting PTSD lol)
Solas 3Plus 9511-153-19 WOT 5200 with either 2 ppl lightly loaded but full fuel or 4 ppl lightly loaded full fuel, just took a few extra seconds to get to 52. 35knots or 40mph.
4500 - 30k/34.5mph 11% slip
4000 - 25k/29mph 17% slip
3500 - 20k/23mph 24% slip
Falls off plane at 16-17knots
Solas Titan HR 4 (SS) 9553-143-17 WOT 5500 (200 over spec) with 2 ppl lightly loaded but full fuel. Figure it will be top of WOT spec once fully loaded, but may creep over once I raise the motor one hole. Will see, this is a loaner prop.
5500 - 36k/41.5mph 4% slip
4500 - 29k/33mph 5% slip
4000 - 24k/27.5mph 10% slip
3500 - 20k/23mph 15% slip
No I havent tried an Enertia 17 or 19 yet. Nor a Rev4. I've been using what I can get on loan from a prop shop, and what I can afford this year and save up to plan for the perfect prop next year.
yes, I now have ~100lb of cannon balls in the bow locker and all my other metal stuff that used to live under the seats in the cuddy lockers, so probably over 200lb of cannon balls, anchors, jigs and wrenches and filters etc for counter balance - and not observable positive net effect at this motor height
BTW, this is my current height, and am going up one hole once I get some 3M 4200 or sikaflex 291. DIY project for me if I get brave enough. But may chicken out and get my mech to do it for me - what's another 500 bucks fml... grrr...
Otherwise, I dont think this boat is a common one out there. I see a few here and there and they are either fitted with an E-Tec 150 or are the inboard version. A buddy of mine had this same boat with a 150 merc optimax and a hi-5 prop for family water sports, no trim tabs. But not feedback about performance from him other than it was a fun boat for tubing. I have heard from other members here through this thread and my past thread about my problems when I was underpowered with the 115. Seems all had issues with stern lift. I needed a foil with the 115 to get on step quicker and to have better trim control and hold plane at relatively low speed. Even then I usually ran at 4800-5000 rpm with the 115 just to get 22-24 knots with the family on board. But if I had buddies onboard to fish west coast, I was running 5000-5200 to hit 22 knots and had to do the seating disco to get on step (everyone to the cuddy lol). Once on step, with any reasonable load at >18 knots, I could always back off the trim tabs and release the outboard trim to optomize trim angle and speed efficiencies etc with no porposiing or spray issues, which is where I'm at now. I have to have the trim tabs 50% engaged and the 150 trimmed all the way under otherwise I have porpoising, and even then the bow has little control in chop unless the trim tabs are slammed down. Before with the 115, I only needed to use the trim tabs for getting out of the hole and side-side balancing, not fore-aft control on step.
I'll never look at a porpoise the same again!
But between adding 100lb of motor and the bigger gear case, and the stuff you've read and seen here in this thread, next steps are to go up one hole to get better overall performance, and get get back trim control from the outboard so I dont have to rely on my trim tabs to do the job.
So it's back to the garage to twist some nuts
Last edited:
brutus
Well-Known Member
Seem like the 4 blade is doing a better job, I am no expert on smaller boats, but the extra weight on the stern and the bigger prop is pushing your stern down( bow gets light ) that’s why you bouncing lol. From your pic( I am no expert) motor looks a bit low still, I was amazed how high I had to raise mine to get it to run decent, not perfect but good enough ( I am still holding on to my jack plate in case) good luckWow, quite the reading mission you went on - appreciated!
I have weighed the boat on the trailer before at the dump (1750kg or 3850lb total), but I have no idea what the boat weighs on it's own - I guess I could do that. Best guess is its around 3000lb.
Tach should be accurate - replaced a few years ago and seems very reasonable across two outboards now.
I did not test any 115 props on the 150 - different gear case size. They fit but looked silly.
Speeds as posted have their units described, but here they are again:
WOT range for the seapro 150 is 4800-5300 (please dont ask or question it - I'm getting PTSD lol)
Solas 3Plus 9511-153-19 WOT 5200 with either 2 ppl lightly loaded but full fuel or 4 ppl lightly loaded full fuel, just took a few extra seconds to get to 52. 35knots or 40mph.
4500 - 30k/34.5mph 11% slip
4000 - 25k/29mph 17% slip
3500 - 20k/23mph 24% slip
Falls off plane at 16-17knots
Solas Titan HR 4 (SS) 9553-143-17 WOT 5500 (200 over spec) with 2 ppl lightly loaded but full fuel. Figure it will be top of WOT spec once fully loaded, but may creep over once I raise the motor one hole. Will see, this is a loaner prop.
5500 - 36k/41.5mph 4% slip
4500 - 29k/33mph 5% slip
4000 - 24k/27.5mph 10% slip
3500 - 20k/23mph 15% slip
No I havent tried an Enertia 17 or 19 yet. Nor a Rev4. I've been using what I can get on loan from a prop shop, and what I can afford this year and save up to plan for the perfect prop next year.
yes, I now have ~100lb of cannon balls in the bow locker and all my other metal stuff that used to live under the seats in the cuddy lockers, so probably over 200lb of cannon balls, anchors, jigs and wrenches and filters etc for counter balance - and not observable positive net effect at this motor height
View attachment 125837
BTW, this is my current height, and am going up one hole once I get some 3M 4200 or sikaflex 291. DIY project for me if I get brave enough. But may chicken out and get my mech to do it for me - what's another 500 bucks fml... grrr...
Otherwise, I dont think this boat is a common one out there. I see a few here and there and they are either fitted with an E-Tec 150 or are the inboard version. A buddy of mine had this same boat with a 150 merc optimax and a hi-5 prop for family water sports, no trim tabs. But not feedback about performance from him other than it was a fun boat for tubing. I have heard from other members here through this thread and my past thread about my problems when I was underpowered with the 115. Seems all had issues with stern lift. I needed a foil with the 115 to get on step quicker and to have better trim control and hold plane at relatively low speed. Even then I usually ran at 4800-5000 rpm with the 115 just to get 22-24 knots with the family on board. But if I had buddies onboard to fish west coast, I was running 5000-5200 to hit 22 knots and had to do the seating disco to get on step (everyone to the cuddy lol). Once on step, with any reasonable load at >18 knots, I could always back off the trim tabs and release the outboard trim to optomize trim angle and speed efficiencies etc with no porposiing or spray issues, which is where I'm at now. I have to have the trim tabs 50% engaged and the 150 trimmed all the way under otherwise I have porpoising, and even then the bow has little control in chop unless the trim tabs are slammed down. Before with the 115, I only needed to use the trim tabs for getting out of the hole and side-side balancing, not fore-aft control on step.
I'll never look at a porpoise the same again!
But between adding 100lb of motor and the bigger gear case, and the stuff you've read and seen here in this thread, next steps are to go up one hole to get better overall performance, and get get back trim control from the outboard so I dont have to rely on my trim tabs to do the job.
So it's back to the garage to twist some nuts
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