I don’t think my boat is hitting the speed it should

[JimS123]

The Mercury Enertia was recommended based on personal experience. It is also listed as applicable for Alpha Sterndrives. The Laser II is listed as optimum for Outboards.

Nevertheless, a quick check showed the laser to be about half the price. I didn't realize there was that big a difference among different models.

Maybe a laser is a better choice. As long as its SS it should be better.

 

[Chopp]

First weigh the boat to be sure its not waterlogged and worth investing in. SS is expensive.

Earlier several posters alluded to a Mercury SS Enertia prop. I bought one last year and wholly crap, what performance!

If your "not great" hole shot means it takes a few more seconds to plane (as opposed to it won't plane at all) then maybe a Doelfin would help.

As previously posted, my last boat with a 3.0 had a prop repitched to give the full 4800 rpm, fixed trim tabs and a Doel to boot. With 3 fat adults, 1 skinny adult and 4 skinny pre-teens (8 people) it would come up on plane in an instant.

Although I'm an outboard guy now, I was always impressed with the performance of the 3 liter 4 banger. Just need the right prop.

Slow out of the hole meaning just slow. Still goes on plane. I weighed the boat and it’s at 3,080 pounds. The trailer says Maki on it, with Sea Ray stamped on it. It has a full tank of gas, which is like 8 gallons, an anchor, a prop, and a few life jackets. The boat should be 1900lb dry... not sure about the trailer weight. Trailer is a bunk style, and it’s steel.

 

[QBhoy]

The Mercury Enertia was recommended based on personal experience. It is also listed as applicable for Alpha Sterndrives. The Laser II is listed as optimum for Outboards.

Nevertheless, a quick check showed the laser to be about half the price. I didn't realize there was that big a difference among different models.

Maybe a laser is a better choice. As long as its SS it should be better.

You are totally Right Jim. I have an enertia on my alpha and my merc outboard. They are great things. But very expensive.
Laser 2’s used to come in 2 forms. One for smaller gearcase outboard and one for alpha and big gearcase outboards. I understand recently that they stopped making them for the large gearcase now.
My thinking is that they are known to be good for most applications and a used good one is about a quarter of the price of an enertia.
If the fella is willing to spend big on an enertia, i for one wouldn’t put him off it...I think they are amazing props and certainly show improvement over any other prop I have or have had. There has been a few of them to compare with

 

[Chopp]

That props got one hell of a price... lol. I’m liking the Laser 2 price tag a lot more. But I don’t want to buy it if the foam is wet. I should also note that there’s a wake board tower added on. Not sure how much that weighs... maybe 100 pounds? Maybe a little more?

 

[JimS123]

Based on your weight data, I'd have to say you're not far off. Any soft spots on the deck? To be sure have a marine surveyor do a moisture meter test.

You get what you pay for. If better performance it the key, one choice. If lower cost is the key, yet another choice.

An Engineering Management Professor once gave me a premise that has stood with me for 40 years:

• You can have it fast
• You can have it cheap
• You can have it good.

Or, pick 2, you can't have all three.

As I said before, go with the Laser II. It should be an improvement. Its your decision whether the Enertia will be cost effective to you.

 

[Chopp]

Based on your weight data, I'd have to say you're not far off. Any soft spots on the deck? To be sure have a marine surveyor do a moisture meter test.

You get what you pay for. If better performance it the key, one choice. If lower cost is the key, yet another choice.

An Engineering Management Professor once gave me a premise that has stood with me for 40 years:

• You can have it fast
• You can have it cheap
• You can have it good.

Or, pick 2, you can't have all three.

As I said before, go with the Laser II. It should be an improvement. Its your decision whether the Enertia will be cost effective to you.

No soft spots. Solid floor. I’ll get a moisture test done just to be sure. Looking at the laser 2 it says: [h=5]MERCURY OUTBOARDS: MERCURY/MARINER 40 BIGFOOT/COMMANT THRUST - 125 HP[/h]

• 40-60 HP BigFoot/Command Thrust (CT) All Years
• 75-125 HP 1978 and Newer
• 15 Tooth Spline
• Note: Flo-Torq III Hub Kit 835257K9 is recommended for 40-60 HP BigFoot/Command Thrust (CT) and 75-115 HP Optimax to reduce clutch rattle

I don't think that’ll fit my alpha drive...

 

[JimS123]

Yup...outboards. That's what I said before.

Contact Mercury marine tech service by phone. They have helped me in the past. Be sure to have your engine model and serial number.

In the interim google mercury's prop selector web site. I don't know how far they go back but maybe they'll show data for a 3.0 115.

 

[Chopp]

Yup...outboards. That's what I said before.

Contact Mercury marine tech service by phone. They have helped me in the past. Be sure to have your engine model and serial number.

In the interim google mercury's prop selector web site. I don't know how far they go back but maybe they'll show data for a 3.0 115.

Sorry, I didn’t see you mentioned outboards. I will contact them tomorrow. And as far as pitch, the prop selector is putting me at a 21P prop. I’m at 4900 rpms, 37mph with my current 19P. My max WOT is 4200-4600. I have another prop for water sports which I rarely do, so I’m just focused on a prop with usually just me in the boat. Do you think a 21 is right? Or maybe a 20?

 

[JimS123]

We all want everything, right? Run right at 4600, awesome hole shot, max top speed and awesome mid range economy. Oh, and it needs to be a cheap prop too...LOL.

You need to lower your rpm. SS will do that even at the same pitch. If you lower it too much you'll lose the hole shot.

Personally, my guess is that a 21 is too tall. A 20 "might" be the best of both worlds, but then you'll have to have a Enertia because they don't make a 20 Laser.

Don't forget the Enertia is a vented prop, so if you decide to waterski one day, maybe you could just pop out the plugs and get it to rev fast and quick. I don't have any experience with Mercs PVS so I can't offer any advice there.

If it were me I'd stick with a 19. What does everyone else say?

 

[Chopp]

We all want everything, right? Run right at 4600, awesome hole shot, max top speed and awesome mid range economy. Oh, and it needs to be a cheap prop too...LOL.

You need to lower your rpm. SS will do that even at the same pitch. If you lower it too much you'll lose the hole shot.

Personally, my guess is that a 21 is too tall. A 20 "might" be the best of both worlds, but then you'll have to have a Enertia because they don't make a 20 Laser.

Don't forget the Enertia is a vented prop, so if you decide to waterski one day, maybe you could just pop out the plugs and get it to rev fast and quick. I don't have any experience with Mercs PVS so I can't offer any advice there.

If it were me I'd stick with a 19. What does everyone else say?

On boatpropellerwarehouse.com it says the Laser 2 comes in 20P and has the vent system... of course that’s if it ends up fitting my alpha drive. I did some reading on the vent system and it seems like that may work wonders. I would think the 20P would be good for the boat... but all I need to know now is how much the diameter matters... my current prop is 14.5” and the laser 2 is 13 1/4” and the Enertia is 13 3/4”

 

[Scott Danforth]

I would verify your tach. even on a 16-1/2 foot boat weighing about 1600#, I couldnt run anything bigger than a 19P

diameter is the last consideration over blade material, blade design, number of blades, pitch, and if it has a cup..... diameter has very very little effect.

 

[JimS123]

On boatpropellerwarehouse.com it says the Laser 2 comes in 20P and has the vent system... of course that’s if it ends up fitting my alpha drive. I did some reading on the vent system and it seems like that may work wonders. I would think the 20P would be good for the boat... but all I need to know now is how much the diameter matters... my current prop is 14.5” and the laser 2 is 13 1/4” and the Enertia is 13 3/4”

The last Mercury prop catalog I have shows only 19 and 21. If they added a 20 now, maybe that's your answer. Merc tech svc should be able to tell you.

 

[dazk14]

1st- your getting a lot of good advise here....
What's clear is you have the need for speed...or at least want to reasonably max out what your setup, totally understandable.
It's probably a good idea to post a pic of the engine cover to verify what you have, though you're looking for a Large Hub (4-3/4") 15 spine STAINLESS prop.
And no, aluminum prop flexing is simply an old wife's tale in the sizes we're discussing.
As you've probably realizing, prop fitting is a black art and your best bet is to start with used props.
With the correct hub kit, there are many more brand/models of props available, just to add confusion.
That said, Jim's suggestion of trying a Laser II makes perfect sense and a great place to start (maybe finish).
Due to the very high gear ratio of your drive, it's fairly common to see them with 21" pitch alum. props, but complaints about hole shot is also common.
For ~$200, or less should be Laser II large hub RH 19', used on ebay,etc.. You can always resell it. The diameter should be ~14", which is the 4-3/4" hub, NOT ~13-1/4" which is the smaller hub that Mercury still produces today.
Here is a part# 48-16544 A40 19P, though it's often not listed.

 

[Chopp]

1st- your getting a lot of good advise here....
What's clear is you have the need for speed...or at least want to reasonably max out what your setup, totally understandable.
It's probably a good idea to post a pic of the engine cover to verify what you have, though you're looking for a Large Hub (4-3/4") 15 spine STAINLESS prop.
And no, aluminum prop flexing is simply an old wife's tale in the sizes we're discussing.
As you've probably realizing, prop fitting is a black art and your best bet is to start with used props.
With the correct hub kit, there are many more brand/models of props available, just to add confusion.
That said, Jim's suggestion of trying a Laser II makes perfect sense and a great place to start (maybe finish).
Due to the very high gear ratio of your drive, it's fairly common to see them with 21" pitch alum. props, but complaints about hole shot is also common.
For ~$200, or less should be Laser II large hub RH 19', used on ebay,etc.. You can always resell it. The diameter should be ~14", which is the 4-3/4" hub, NOT ~13-1/4" which is the smaller hub that Mercury still produces today.
Here is a part# 48-16544 A40 19P, though it's often not listed.

I appreciate the feedback. Yes, you guys are awesome. Just trying to max out the set up. My local marina will be checking and adjusting timing in a few days, and I’ll have them verify the tach. If the timing is adjusted and the tach is accurate, I’ll take it out and see if any changes are made in the water. I’ll try to get a used laser, if not try out the Enertia, and I really do appreciate you guys being patient and help pointing me to the Laser and the Enertia props. I appreciate it!