Boat just WON'T PERFORM with a 200+hp Engine: WHY?

[EuropeanAM]

Since I've been seeing boats, answering posts, and talking to NUMEROUS folks that have been having difficulties achieving good performance, I'm going to take a few moments to share the top few reasons we are seeing:

1. Demand Linear not achieving 100% Demand (hotfoot and throttle cable improperly set-up)

2. WEIGHT where it's not supposed to be, NO WEIGHT where it IS supposed to be. SERIOUSLY!!! If you mount an Ultrex, (3) graphs, and custom brackets for 3 said graphs on the BOW, you should NOT be surprised when your boat does not perform. You've literally tacked a couple hundred pounds on the BOW of the boat. Then... some of the same boats swap out 3-5 Lead-Acid (or AGM) batteries to Lithiums, often pulling as much (or more) weight from the stern of the boat. This causes the stern to ride HIGHER, the bow to ride LOWER, resulting in more boat in contact with the water at top speed. No reasonable amount of trim will ever compensate for this.

3. Excessive Setback (especially when combined with #2)

4. Over-propped

5. Dragging Power Poles


While there may occasionally be an actual engine problem, it is completely UNREALISTIC to expect an engine to carry the loads/weight-distribution that is described in #2 and perform even reasonably well. If your bow looks like the image below... it's set up for FISHING (not for running to the fish).



(Image posted by Meleagris1)

*** Simple Testing Hint: If you suspect your boat may be victim of #2, remove as much gear as possible from the bow. Add 80-120# of SAND (double-bag the sand) and place it on top of the back deck, at the very back. Go run the boat and try different trim/jackplate heights... if you see IMPROVEMENT (at all) in performance, you are on the right track.

[Rubrail]

What are the symptoms of #1? Or how would you know it needs to be adjusted?

[06 SB]

Not to mention the aerodynamic drag of all the hardware on the bow.

[mactlman]

What are the symptoms of #1? Or how would you know it needs to be adjusted?

Not being able to hit 6200k rpms. Or very close with correct prop

[PMantle]

I have a spotlock TM but only one graph up front. Switched to three lithiums for all needs. Makes me wonder if I should always run a full gas tank.

[EuropeanAM]

I have a spotlock TM but only one graph up front. Switched to three lithiums for all needs. Makes me wonder if I should always run a full gas tank.

Might want to try the sand-bag trick... it targets the weight to the same general area as the (removed) lead-based batteries.

[PMantle]

Might want to try the sand-bag trick... it targets the weight to the same general area as the (removed) lead-based batteries.

I fish alone a lot. The left side could probably use that.

[Rob4AU]

Since I've been seeing boats, answering posts, and talking to NUMEROUS folks that have been having difficulties achieving good performance, I'm going to take a few moments to share the top few reasons we are seeing:

1. Demand Linear not achieving 100% Demand (hotfoot and throttle cable improperly set-up)

2. WEIGHT where it's not supposed to be, NO WEIGHT where it IS supposed to be. SERIOUSLY!!! If you mount an Ultrex, (3) graphs, and custom brackets for 3 said graphs on the BOW, you should NOT be surprised when your boat does not perform. You've literally tacked a couple hundred pounds on the BOW of the boat. Then... some of the same boats swap out 3-5 Lead-Acid (or AGM) batteries to Lithiums, often pulling as much (or more) weight from the stern of the boat. This causes the stern to ride HIGHER, the bow to ride LOWER, resulting in more boat in contact with the water at top speed. No reasonable amount of trim will ever compensate for this.

3. Excessive Setback (especially when combined with #2)

4. Over-propped

5. Dragging Power Poles


While there may occasionally be an actual engine problem, it is completely UNREALISTIC to expect an engine to carry the loads/weight-distribution that is described in #2 and perform even reasonably well. If your bow looks like the image below... it's set up for FISHING (not for running to the fish).



(Image posted by Meleagris1)

*** Simple Testing Hint: If you suspect your boat may be victim of #2, remove as much gear as possible from the bow. Add 80-120# of SAND (double-bag the sand) and place it on top of the back deck, at the very back. Go run the boat and try different trim/jackplate heights... if you see IMPROVEMENT (at all) in performance, you are on the right track.

This is all very true but in my case I removed a Mercury 200 opti and replaced it with a new Mercury 200 v8 4 stroke and did not change anything other than the motor and went from 74mph empty with 200 the 2 stoke to 60mph empty with the new 200 4 stroke. After numerous back and forth trips to the dealership where the motor was purchased the owner of the dealership and his lead mechanic went to the water with me and the boat and took numerous props, jack plate wrench and a laptop and conclusion was the motor is just weak. Mercury has no answer either. The motor runs perfect just does not perform as it should. Croxton fixed me a prop that helps but it won't turn over 5600 rpms without over trimming regardless of prop or motor height. I could run 67-69mph all day with the 200 2 stroke tournament loaded with 2 average sized men and now with the same load I run around 55mph.

[Pulsare2020]

This is all very true but in my case I removed a Mercury 200 opti and replaced it with a new Mercury 200 v8 4 stroke and did not change anything other than the motor and went from 74mph empty with 200 the 2 stoke to 60mph empty with the new 200 4 stroke. After numerous back and forth trips to the dealership where the motor was purchased the owner of the dealership and his lead mechanic went to the water with me and the boat and took numerous props, jack plate wrench and a laptop and conclusion was the motor is just weak. Mercury has no answer either. The motor runs perfect just does not perform as it should. Croxton fixed me a prop that helps but it won't turn over 5600 rpms without over trimming regardless of prop or motor height. I could run 67-69mph all day with the 200 2 stroke tournament loaded with 2 average sized men and now with the same load I run around 55mph.

I was going to ask if both engines had the same lower unit, but 10 - 14 mph is a lot for a different lower unit and I doubt you had a Sportsmaster on the Optimax anyway. Does the 200 V8 have the larger 5.44" lower unit? I doubt that would even cause it. If that motor is really that weak, I hope Mercury takes care of you.

[Crappie Bob]

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

[Unravels]

I have a 200 4s on a 2021 Basscat Pantera 2 and spent some time chasing those last 5 mph, I am the best driver by no means, and the chinewalk starts in pretty good about 68, but is getting easier to manage. No poles, has AGM batteries, not loaded down, one graph up front and a Lowrance ghost. Is/was hard to get the RPMs up over 6k. Started with a 24p fury 3, couldn’t get over 56-5700 tried raising jack plate. Didn’t help. Went to a 23 fury 3 dealer swapped out for me, they checked and made sure 100% on throttle, played around with jackplate, my dealer Boatmasters is awesome. Now it will get up to about 5900 and 69-70. I tried a 23p trophy plus (4 blade) and can get 68 at about 6-6100. I have heard of other people getting more speed out of this boat and motor, closer to 75, but we’re Optis. Seems like the 2 stroke guys were getting more speed.

Personally I think the issue lies in a large V8 designed to make a lot more horsepower being choked down with smaller throttle and software to 200 hp. It cant breathe when it gets up to speed. It likely isn’t making peak torque and hp at the rpm that the 2s motors did, I.e. stops pulling at higher RPM compared to a lower displacement 2 stroke, probably hitting software limiter. According to smog certification website looks like motor (outboard 4.6 V8) on lowest HP rating is making 298 lb peak torque at 4k rpms. If motor is making that much torque and limited to 200 hp, something has to be choked down as the RPM goes up or it would exceed the horsepower rating. If I am right, configuration is only going to get you so far.

https://ww2.arb.ca.gov/sites/default...w-001-0490.pdf

My minimal experience with building/modifying engines is only with motorcycles, dirt bikes and 4 cylinder bmw engines. They were all pretty small displacement relative the this motor, but goal was always move as much air as possible at a high rpm, avoid heat and avoid detonation, and as a byproduct make more power. This engine is doing the opposite of that by design because this same motor can be configured mostly by software and throttle body to be a 200-225-250-300, all on the same basic engine. So kind of seeing this motor as a high torque low hp engine, will have good holeshot, good acceleration/midrange, but the designed restrictions to meet hp limitation will not let it make any real power up top. On the other side of that, with this motors inherent capability, they all should make 220hp as a product of software limitation if they are allowed 10% margin on hp rating. Heck, maybe mine is making 220 hp I have no way to check. Either way, it doesn’t have that top end rush I think people are used to and enjoy. On the other hand it is operating way under capacity and hopefully will last a long time because it’s not at it’s limit. Also probably because of this it is pretty efficient, I am get about 10 gph at 50 mph cruise speed, vs 18-20 gph between 65-70.

At this point, I am happy with my boat, it is a 70 mph (GPS) boat which is plenty fast for a 19 ft bass boat. Hole shot is great and it is a really quick, fast accelerating, boat. Just need to use and enjoy it vs trying to get every last mph I can out of it.

[EuropeanAM]

Forget the carb certifications. Those figures are simply a recording of the output of the engine at a specific RPM, and are NOT indicative of it's PEAK torque and horsepower.

That being said- yours (Unravels) sounds reasonably respectable.

Rob 4AU... something is definitely wrong in your case if what you say is accurate.

[Bassin Billy]

I plan on getting a few of the heavy rubber coated olympic weights and dropping one in each of the rear storage compartments. I figure as large as they are I should be able to drop a 45lb weight in each one and still not give up much room. Hoping that helps me a little. Keeping in mind that on the Caymas, we do not have a true rear fuel tank as with other models. I have 2 lowrance 9s on the bow, I don't have any real additional weight nor have have power poles, etc...figured my 19 with 225 would be pushing 65-68 easily. Not the case.

[EuropeanAM]

Good idea.

[PMantle]

I plan on getting a few of the heavy rubber coated olympic weights and dropping one in each of the rear storage compartments. I figure as large as they are I should be able to drop a 45lb weight in each one and still not give up much room. Hoping that helps me a little. Keeping in mind that on the Caymas, we do not have a true rear fuel tank as with other models. I have 2 lowrance 9s on the bow, I don't have any real additional weight nor have have power poles, etc...figured my 19 with 225 would be pushing 65-68 easily. Not the case.

I thought of that too. Please report back. I would rather not have something happen to a sand bag and have to clean that up.

[cclucky5]

3B011653 2021 Mercury 250LPXS TM Fury 23 3 Blade Also have a Trophy plus 24 four blade. 5900 is really the highest rpm ever but past weekend 5600 5800. Water pressure 5 at idle 20 at wot analog gauges. This is a re-power on a 2017 Triton 21trx replacement hull which I believe is a lot heavier than the 2014 was but immediately lost 5 mph on the 2 stroke 250 pro xs. No poles AGM cranking and 3-27 wet cells. Ultrex 112 one 9” graph up front. I have taken half of the tackle I once carried to lighten the load. This past weekend fished 3 days in a row and rain soaked first day but even when dry was only running 61 gps and just doesn’t feel like on pad. 550 pounds Of me and partner but my question is how much power should you lose to extra weight. When I went to the 23 fury I finally started getting by myself 5900 and breaking 70. Also had my dealer check to make sure throttle was opening all way at first oil change. I’m question if my hot foot has something to do with it so will get that checked but again question is how much does weight affect rpm. Thanks

[EuropeanAM]

3B011653 2021 Mercury 250LPXS TM Fury 23 3 Blade Also have a Trophy plus 24 four blade. 5900 is really the highest rpm ever but past weekend 5600 5800. Water pressure 5 at idle 20 at wot analog gauges. This is a re-power on a 2017 Triton 21trx replacement hull which I believe is a lot heavier than the 2014 was but immediately lost 5 mph on the 2 stroke 250 pro xs. No poles AGM cranking and 3-27 wet cells. Ultrex 112 one 9” graph up front. I have taken half of the tackle I once carried to lighten the load. This past weekend fished 3 days in a row and rain soaked first day but even when dry was only running 61 gps and just doesn’t feel like on pad. 550 pounds Of me and partner but my question is how much power should you lose to extra weight. When I went to the 23 fury I finally started getting by myself 5900 and breaking 70. Also had my dealer check to make sure throttle was opening all way at first oil change. I’m question if my hot foot has something to do with it so will get that checked but again question is how much does weight affect rpm. Thanks

This one really needs it's own separate post as it's likely to involve more than a single comment. Thanks!

[mactlman]