# What prop 2019 Hells Bay Marquesa/Mercury 115 ProXS



## windblows

What type of speed are you seeing at WOT? I have a 115 ProXS on my boat (different boat) but am running a 3 blade 20p prop that I've had some work done to. I've had some cup added to it because I was easily hitting max RPMs of 5750 (I have the 2015 ProXS that is a 2 stroke.) Now I can hit the max RPMs and see about 48-49mph tops. Hole shot is acceptable.


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## Zeke Sieglaff

windblows said:


> What type of speed are you seeing at WOT? I have a 115 ProXS on my boat (different boat) but am running a 3 blade 20p prop that I've had some work done to. I've had some cup added to it because I was easily hitting max RPMs of 5750 (I have the 2015 ProXS that is a 2 stroke.) Now I can hit the max RPMs and see about 48-49mph tops. Hole shot is acceptable.


I am seeing 44-45 at 47-4800 rpms. I should easily see 49-51 with the right prop.


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## windblows

No doubt you need to move up in pitch. If you stick with a 4 blade, I would think you would want to be in the 23-24 pitch range. Maybe 22 in a 3 blade.


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## flyclimber

@MariettaMike


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## Forcefed

For starters you don’t want to go up in pitch if the motor isn’t turning 5000 rpm. I believe the recommended redline on the XS merc 115 fs’s is 6300. Are you able to trim the motor up some at speed or does the prop cavitate ? 

If you can trim out to get the bow up and less wetted surface you should pick up some speed compared to the engine being trimmed all the way down. If that rpm is with the engine trimmed for best speed you need to drop down in pitch, not go up.


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## Zeke Sieglaff

Forcefed said:


> For starters you don’t want to go up in pitch if the motor isn’t turning 5000 rpm. I believe the recommended redline on the XS merc 115 fs’s is 6300. Are you able to trim the motor up some at speed or does the prop cavitate ?
> 
> If you can trim out to get the bow up and less wetted surface you should pick up some speed compared to the engine being trimmed all the way down. If that rpm is with the engine trimmed for best speed you need to drop down in pitch, not go up.


New development.... spoke with my mercury mechanic and I think it may be more of an issue with the throttle bottoming out on the console not allowing it to get to WOT. Hopefully I'm propped right and just need to shim the binnacle or adjust the throttle cable....


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## windblows

Doh


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## HPXFLY

not a prop question, but you guys running a 115xs, what lower are you running ? command thrust ? especially interested on the marquesa


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## Zeke Sieglaff

HPXFLY said:


> not a prop question, but you guys running a 115xs, what lower are you running ? command thrust ? especially interested on the marquesa


I am running the standard (not command thrust) at the strong suggestion of Hells Bay. It turns out I have full range of throttle, so I am now back to what is hopefully a prop issue, not a motor issue.


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## kamakuras

No offense by this question but are you trimming up to get the bow up and boat aired out? This should be the right prop for you. I run the regular Merc 115 with 18p 4 blade and hit 5.9-6k rpm on my Marquesa. Also run 21p 3blade PT same rpm range, higher top end. Paul at HB didn't just randomly pick a prop for your boat, he wet tests every one before delivery. They have sold several others with the ProXS with that same prop with no issues to my knowledge. Where are you located? I have two spare power techs for my Marquesa with Merc hub you could try if you want. 4 and 3 blade.


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## Zeke Sieglaff

No offense taken, this one has been a head scratcher for me. Yes, I have fooled a bunch with the trim. I am confident now that it is the right prop after discussing the issue with HB. I am in Placida. When they wet tested the boat it turned 6000 rpm with 49mph.I can not come close to that. I will be exploring further with my mercury mechanic to rule out throttle cable issues. Thanks for the offer, if you're close by I may take you up.


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## kamakuras

I am in Jupiter but will be going through St Pete to pick up a new Tohatsu Thursday morning next week. If you have an hour in the morning early to run it shoot me a pm.


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## tailchaser16

Zeke Sieglaff said:


> When they wet tested the boat it turned 6000 rpm with 49mph.


When "they" tested it, was it in fresh water or in salt?


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## Zeke Sieglaff

Fresh water. I've been to my mechanic who has confirmed that I am getting wide open throttle as well. Taking the skiff back to HB in a couple weeks for them to do further testing.


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## kylet

windblows said:


> No doubt you need to move up in pitch. If you stick with a 4 blade, I would think you would want to be in the 23-24 pitch range. Maybe 22 in a 3 blade.


Dude...


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## kylet

Zeke Sieglaff said:


> New development.... spoke with my mercury mechanic and I think it may be more of an issue with the throttle bottoming out on the console not allowing it to get to WOT. Hopefully I'm propped right and just need to shim the binnacle or adjust the throttle cable....


Ok now I’ve got to see pics of your console


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## kylet

Zeke Sieglaff said:


> I am seeing 44-45 at 47-4800 rpms. I should easily see 49-51 with the right prop.


These numbers blow me away. I get why it was suggested that maybe your throttle was not getting full range. With that kind of max rpm it would have to be something wild, for instance my other two initial questions were does this guy have so much weight he’s about to sink it or is he mistakenly running with the tabs all the way down. I get that those are extreme but topping out a 4800 rpms because of incorrect prop is extreme. For instance I’d have a hard time believing that if it was a prop issue hampering rpm that much, that you even be able to get it on plane. Then add the fact that you are within 2-3 mph of what most fishing loaded marquesas are going to top out at.

Please update when you get it figured out. This ranks right up there with unsolved mysteries for me.


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## Zeke Sieglaff

kylet said:


> These numbers blow me away. I get why it was suggested that maybe your throttle was not getting full range. With that kind of max rpm it would have to be something wild, for instance my other two initial questions were does this guy have so much weight he’s about to sink it or is he mistakenly running with the tabs all the way down. I get that those are extreme but topping out a 4800 rpms because of incorrect prop is extreme. For instance I’d have a hard time believing that if it was a prop issue hampering rpm that much, that you even be able to get it on plane. Then add the fact that you are within 2-3 mph of what most fishing loaded marquesas are going to top out at.
> 
> Please update when you get it figured out. This ranks right up there with unsolved mysteries for me.


I've been a guiding since 1994, this is my 4th skiff and 2nd HB. No excessive weight or tabs, lithium-ion battery rig (very light) and minimal gear. I weigh 160 pounds soaking wet...I am totally vexed. I will let you know after the crew at HB gets to the bottom of it.


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## kylet

Zeke Sieglaff said:


> I've been a guiding since 1994, this is my 4th skiff and 2nd HB. No excessive weight or tabs, lithium-ion battery rig (very light) and minimal gear. I weigh 160 pounds soaking wet...I am totally vexed. I will let you know after the crew at HB gets to the bottom of it.


To only be getting 70-75% of max rpm at wot it has to be something major. That’s what I was getting at. The 30-40 lbs of weight savings in a 24v lithium setup won’t affect that. If it pitch were that’s easily a 3-4 pitch drop.
What are you using for you measurements of mph and rpm? With a 19 pitch prop you’d need closer to 5800 rpm’s to achieve 45 mph. That would be with pretty minimal prop slip. Maybe it’s just a faulty gauge?
I wasn’t implying you don’t know what you’re doing... just trying to show how extreme those peak numbers are. Like even if that prop were made of tungsten, I’d think that engine would still spin it faster than that. Like I said earlier, I don’t really have a clue what could cause those numbers, but I guess if it were me I’d with a new warranty I’d hope for a faulty gauge or computer.


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## Zeke Sieglaff

kylet said:


> To only be getting 70-75% of max rpm at wot it has to be something major. That’s what I was getting at. The 30-40 lbs of weight savings in a 24v lithium setup won’t affect that. If it pitch were that’s easily a 3-4 pitch drop.
> What are you using for you measurements of mph and rpm? With a 19 pitch prop you’d need closer to 5800 rpm’s to achieve 45 mph. That would be with pretty minimal prop slip.
> I wasn’t implying you don’t know what you’re doing... just trying to show how extreme those peak numbers are. Like even if that prop were made of tungsten, I’d think that engine would still spin it faster than that. Like I said earlier, I don’t really have a clue what could cause those numbers, but I guess if it were me I’d with a new warranty I’d hope for a faulty gauge or computer.


Speed is MPH coming from Simrad GPS and RPM is coming from Mercury multi function gauge... Agreed, something is WAY off somewhere.


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## kylet

Zeke Sieglaff said:


> Speed is MPH coming from Simrad GPS and RPM is coming from Mercury multi function gauge... Agreed, something is WAY off somewhere.


Yeah. Keep us posted. Blows my mind reading it.


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## Zeke Sieglaff

kylet said:


> Yeah. Keep us posted. Blows my mind reading it.


Well, skiff is at HB for diagnosis...stay tuned.


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## Zeke Sieglaff

kylet said:


> Yeah. Keep us posted. Blows my mind reading it.


Finally got my skiff back, Mercury rep ran the boat hooked up to diagnostics and motor checked out fine. Dropped down to a 3 blade Vengeance 18 prop and boat acts TOTALLY different. Much better acceleration and lift. Unfortunately it has been blowing and rainy since I picked it up, but so far I've seen 5500 and 49mph in less then ideal conditions. Prop issue all along. Will probably look into a higher performance prop, either a NRS or PTR Power Tech 3 blade after I can establish better data with current prop.


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## kylet

Zeke Sieglaff said:


> Finally got my skiff back, Mercury rep ran the boat hooked up to diagnostics and motor checked out fine. Dropped down to a 3 blade Vengeance 18 prop and boat acts TOTALLY different. Much better acceleration and lift. Unfortunately it has been blowing and rainy since I picked it up, but so far I've seen 5500 and 49mph in less then ideal conditions. Prop issue all along. Will probably look into a higher performance prop, either a NRS or PTR Power Tech 3 blade after I can establish better data with current prop.


That’s great that it’s working for you. I’m just as confused as before. I really think somethings screwy with your gauge. You have to be getting better rpms than 5500 to see 49. You can do the math with a 18 inch/revolution prop at 5500 revolutions per minute on a 2.07:1 gearcase, if there were no prop slip (no boat weight, no water resistance, no air resistance), you’d have a absolute maximum speed of 45.2 mph. Did HB give you any explanation other than “here try this prop”? Your new numbers, although the speed is incredible, are equally as crazy as the ones before you took it to them.


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## No Bait / Lures Only

Gotta jackplate?


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## BCPD199

Reviving this thread. HB just finished my boat and water tested it. Salesman said he got 5200 RPMs and 45 MPH. Merc Spitfire 19" prop. He said he couldn't trim it up much and that after I took it home and filled the tank it would go higher/faster. I told him 23 more gallons of fuel in the bow wasn't going to increase my RPMs by a thousand. Don't want pay and take the boat until it's dialed in right. What was your final fix?


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## Steve stepp

BCPD199 said:


> Reviving this thread. HB just finished my boat and water tested it. Salesman said he got 5200 RPMs and 45 MPH. Merc Spitfire 19" prop. He said he couldn't trim it up much and that after I took it home and filled the tank it would go higher/faster. I told him 23 more gallons of fuel in the bow wasn't going to increase my RPMs by a thousand. Don't want pay and take the boat until it's dialed in right. What was your final fix?


Putting weight in the bow area will not make more rpms.. HB is a good company and they should be able to fix your problem. With 115 hp on a 18’ HYDRASTEPP we run 60 mph plus but its a performance hull design with two people load .. but H B is a great boat company


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## BCPD199

Steve stepp said:


> Putting weight in the bow area will not make more rpms.. HB is a good company and they should be able to fix your problem.


We know that; but, not sure if he knew that! No problems with HB. We're waiting for Merc to ship them a Spitfire in 17" and we'll see if that doesn't fix it. I just don't see how the Yammie boys are getting 50 mph out of her. Run a prop slip calculator and that's damn near impossible.


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## kylet

BCPD199 said:


> We know that; but, not sure if he knew that! No problems with HB. We're waiting for Merc to ship them a Spitfire in 17" and we'll see if that doesn't fix it. I just don't see how the Yammie boys are getting 50 mph out of her. Run a prop slip calculator and that's damn near impossible.


On a cold freshwater lake I've seen 51 with the SCD321 and a load optimized for top speed. I cant remember as that was a few years ago but I think I was only turning between 5900 - 6000 rpms. I run a SCD419 and I've seen 49 out of it turning between 6100 and 6200. The big deal with that was I was able to get full WOT without any tabs. When I get some time I'm going to run a Solas prop in both 19 and 21, and I'm going to run a 3 blade in 20p. When I do , I'll let yall know what comes of it.


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## BCPD199

Thanks kylet. Even though the Merc is a larger displacement engine, it doesn't seem as hot as the Yammie SHO. I can't turn up an 18" 3 blade Vengeance past 5800. I can't imagine the lower unit gear ratio difference would cause that much difference (Merc - 2.07 vs Yam - 2.15). I do know that the SCD prop is a semi cleaver blade and according to Marcus at PowerTech, an engine can turn up another 2" of pitch. Right now they are out of stock on most props and just beginning to ramp up production again. We're going to try a SCD418 when they do.


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## SkiffaDeeDooDah

A friend of mine has a Maverick HPX-V 18 with a 2017 Yamaha 115 SHO (no jack plate). The HPX-V 18 is a bit heavier than the HB Marquesa. His HPX/SHO combo spins a Yamaha Pro Series 13.5 x 21 at 6200 to 6300 RPM, at 54 mph. On the same boat, he also runs a Merc Spitfire X7 12.7 x 21 that he had trimmed down and lab finished by Mercury Racing to end up at about 20 pitch, that he can also spin up to 6200-6300 RPM. The HB/Merc 115 ProXS combo should be able to reach the maximum recommended RPM and perform well with a Merc Spitfire X7 12.7 x 19p. I'm no expert mechanic, but I have had a similar issue on my 2016 Hewes Redfisher 16 with a 115 SHO. The problem was fuel flow restriction and fuel tank venting problems. The new EPA mandated carbon cannister installed on the vent hose line became flooded and saturated with fuel. The saturated carbon cannister was not allowing the fuel tank to breathe like it should, and was slowing down fuel flow to the motor. The second fuel flow restriction was caused by a sticky anti-siphon valve on the tank which would not allow enough fuel flow for the engine to reach maximum RPM. Slower speeds and idling ran fine. In both cases, these devices were temporarily removed for testing, and the results were amazing! Throttle response was better than ever. Maximum RPMs and speed were easily reached. My Redfisher 16 w/ 115 SHO was quite a bit heavier than a HB Marquesa, and I was reaching 50 mph at 6100 RPM with the Merc Spitfire X7 19 pitch. Just some ideas to add to your list of things to check out.


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## BCPD199

Appreciate your response. I can't turn a 19" Spitfire past 5000 RPM. The boat is new so I can't believe the carbon cannister is filled; but, fuel restriction is definitely something to look at. I know from the computer, I'm getting 100% throttle opening. I'm going to pull the anti siphon valve and check that. Thanks!


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## SkiffaDeeDooDah

BCPD199 said:


> Appreciate your response. I can't turn a 19" Spitfire past 5000 RPM. The boat is new so I can't believe the carbon cannister is filled; but, fuel restriction is definitely something to look at. I know from the computer, I'm getting 100% throttle opening. I'm going to pull the anti siphon valve and check that. Thanks!


Thank you. Sounds good! If the carbon canister is easy to get to, as a test, you could pull the hose off of the end closest to the fuel tank. If any fuel drips out - it has been flooded and is ruined. If that is the case, you could temporarily install a 3/8" x 3/8" brass barbed coupler in its place and do a test run. To test fuel flow without the ASV, you could install one of these fittings in its place (of correct size with zero restriction) and run the boat again:


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## Zeke Sieglaff

UPDATE...I bit the bullet and bought a command thrust lower unit and Tempest 23 and it's a totally different boat. I have not had the time to properly run it out, but saw 49 mph in significant chop. Gets on plane faster, rides higher. If you are considering a Marquesa with a Mere 115 props, get the command thrust lower unit. Insane difference.


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