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Hey guys, hope everyone is staying safe. Looking for some wisdom on how to get the top speed of my boat up. Currently running a 90hp Evinrude Etec on 1650 Crestliner Fish Hawk. I was out last night with a passenger and only getting 30.5mph trimmed at WOT and getting 5500rpms. I have an aluminum 14x17 prop. I’ve read online that I should be getting closer to 40mph with a boat and motor of this size . Would switching to a different aluminum prop get me closer to the mark or would I need to go stainless to get there? Any help is appreciated. 

Edited by Musky Plug

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Check the boat for deformities on the back edge called a hook. Remove all excess weight that you have stuffed into the boat over the years. Size and change prop to a stainless steel. Out of all of these your biggest gain will be removing all of the extra crap off the boat that you do not use. Realistically you will not gain 10 mph unless you have a major issue slowing down the boat. For example a Ranger boat with 150 HP GTX (racing series motor) stainless cupped prop with little  to no extra weight is doing 58 mph with a stainless and loses only 3 mph with an aluminum prop. The bottom of a bass boat in this series runs on just a pad when on plane with about a 6 x 4 ft area actually touching the water. your boat will have a much larger wetted surface and will have less improvement on changes. 

 

Art

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You are not far off max rpm so props will not help too much.  You may get a few mph faster with a ss prop. But I would look for other problems.  Like checking motor heights or something else that causing drag.   Or go on a diet. Lol. I mean the boat lose weight 

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Seems slow, how are you measuring speed ? it could be off and you are going faster in reality

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Well first you may havr trimmed to high . Motor height may need correction go out and play with trim settings higher isnt always better you want to keep nose slightly up and boat flat as possible for speed

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57 minutes ago, aplumma said:

Check the boat for deformities on the back edge called a hook. Remove all excess weight that you have stuffed into the boat over the years. Size and change prop to a stainless steel. Out of all of these your biggest gain will be removing all of the extra crap off the boat that you do not use. Realistically you will not gain 10 mph unless you have a major issue slowing down the boat. For example a Ranger boat with 150 HP GTX (racing series motor) stainless cupped prop with little  to no extra weight is doing 58 mph with a stainless and loses only 3 mph with an aluminum prop. The bottom of a bass boat in this series runs on just a pad when on plane with about a 6 x 4 ft area actually touching the water. your boat will have a much larger wetted surface and will have less improvement on changes. 

 

Art

 

52 minutes ago, Terry said:

You are not far off max rpm so props will not help too much.  You may get a few mph faster with a ss prop. But I would look for other problems.  Like checking motor heights or something else that causing drag.   Or go on a diet. Lol. I mean the boat lose weight 

LOL.

Last night I had myself, a passenger, full tank, 3 batteries, and tackle bags trolling motor and excluding the tackle and trolling motor weight was around 600+LB. 200each per passenger, 100lb for gas 60L, and 60lb per batt. So that more then likely is the problem? The motor is set on the second hole from the top, which I’ve read is the norm for a boat like this? 

 

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43 minutes ago, dave524 said:

Seems slow, how are you measuring speed ? it could be off and you are going faster in reality

I use my graph. Humminbird helix 9 g3n

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18 minutes ago, ecmilley said:

Well first you may havr trimmed to high . Motor height may need correction go out and play with trim settings higher isnt always better you want to keep nose slightly up and boat flat as possible for speed

I’ve been out a few times and messed around with this and where I had last night seems to the “spot”. Any higher and I feel the boat start to slow down. Could it be the height the motor is mounted at? 

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1 hour ago, Musky Plug said:

 Currently running a 90hp Evinrude Etec on 1650 Crestliner Fish Hawk.

I used to have the same boat with a 90 HP Merc 4 stroke and would get about 43 mph with just me in the boat and drop to around 39 with a passenger.

Motor had an aluminum prop but don't recall the specs.

You should for sure get lots more speed with your set-up.

Edited by lew
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2 minutes ago, lew said:

I used to have the same boat with a 90 HP Merc 4 stroke and would get about 43 mph with just me in the boat and drop to around 39 with a passenger.

Motor had an aluminum prop but don't recall the specs.

You should for sure get lots more speed with your set-up.

Yes, I agree. From what I’ve read online I should be in or around there. 

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3 hours ago, Musky Plug said:

Yes, I agree. From what I’ve read online I should be in or around there. 

Also.double check gps. Had this issue few weeks ago the gen2 hds was reading 9mph slower than actual. 

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Motor height is crucial as I believe most motors are mounted to low . Ur motor should cavitation in a hard turn at full speed with motor trimmed . That being said a good boat operator knows this and will trim down in a turn . Max rpms also very important .i would go down 1 size in pitch and that will up ur rpms by about 200 .aluminum props can also get wore and just flex to much .. 

just my 2 cents 

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Lund Rebel 1650 with a 2017 90 etec , stainless prop , seems to max out anywhere from 37 to 40 at max rpm with various weight scenarios .

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If you don’t know the history of a prop it might not be as stamped.  I will not use an aluminum prop on an engine that gets a lot of use.   
show us a picture of the engine on the back of the boat.  

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It's clear your boat could be prop better.

To start put everything in boat you would have, buddy,livewells full,battery's,rod reel tackle.

From what you say 30 mph unacceptable.

A 4 blade prop and stainless will carry the weight better.

Can you borrow a prop or goto Prop Guy in Buckhorn you can try props until you find the right one.

You don't really want  top speed. Acceptable hole shot and reasonable speed. Then think about your use Lake O or Simcoe you need grip.

So when faced with mountain of water you can go.

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16'8 Alumacraft with 90 hp Yamaha....cheap prop as I don't really care about getting an extra mph or 3. Alone I will go 42 mph and with someone around 38...so something is definitely not right whether it be the gps or the boat/motor

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3 hours ago, Rustic-Fisher said:

Lund Rebel 1650 with a 2017 90 etec , stainless prop ,

Just curious, did you have an aluminum prop 1st then switch to stainless and if so, what speeds did you see with the aluminum ?

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We always under estimate weight onboard. An average 12V battery is closer to 100 lbs than 60 lbs. Every ounce counts. One gent that went into our neighbourhood marine guy was complaining about the exact same thing, not enough speed. Little Buddy reached into a storage box and pulled out a full gallon of 2 stroke oil and asked the customer '" Did you count this at around 8 pounds?" Nope, forgot. 

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7 hours ago, Heavy Current said:

Motor height is crucial as I believe most motors are mounted to low . Ur motor should cavitation in a hard turn at full speed with motor trimmed . That being said a good boat operator knows this and will trim down in a turn . Max rpms also very important .i would go down 1 size in pitch and that will up ur rpms by about 200 .aluminum props can also get wore and just flex to much .. 

just my 2 cents 

From what I’ve read online the way it’s mounted currently is how it’s usually done for a boat Like this. 

 

On 9/12/2020 at 2:55 PM, ecmilley said:

Also.double check gps. Had this issue few weeks ago the gen2 hds was reading 9mph slower than actual. 

I will double check this with the other graph and my phone. 

 

5 hours ago, glen said:

If you don’t know the history of a prop it might not be as stamped.  

Stamped with the size and pitch? 

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5 hours ago, Garnet said:

It's clear your boat could be prop better.

To start put everything in boat you would have, buddy,livewells full,battery's,rod reel tackle.

From what you say 30 mph unacceptable.

A 4 blade prop and stainless will carry the weight better.

Can you borrow a prop or goto Prop Guy in Buckhorn you can try props until you find the right one.

You don't really want  top speed. Acceptable hole shot and reasonable speed. Then think about your use Lake O or Simcoe you need grip.

So when faced with mountain of water you can go.

No I wouldn’t be able too. I’ve called around locally and everyone has told me I must buy them they won’t lend them. And unfortunately that is to far from where I’m located. I would just like to get the most out of my motor and from what I’ve read I am not.  

 

4 hours ago, Rizzo said:

16'8 Alumacraft with 90 hp Yamaha....cheap prop as I don't really care about getting an extra mph or 3. Alone I will go 42 mph and with someone around 38...so something is definitely not right whether it be the gps or the boat/motor

Will double check gps when I get out next and the potential weight issue. 

 

2 hours ago, lew said:

Just curious, did you have an aluminum prop 1st then switch to stainless and if so, what speeds did you see with the aluminum ?

X2. 

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1 hour ago, Old Ironmaker said:

We always under estimate weight onboard. An average 12V battery is closer to 100 lbs than 60 lbs. Every ounce counts. One gent that went into our neighbourhood marine guy was complaining about the exact same thing, not enough speed. Little Buddy reached into a storage box and pulled out a full gallon of 2 stroke oil and asked the customer '" Did you count this at around 8 pounds?" Nope, forgot. 

I’ve weighed the current batteries I’m using for the TM and they are right around 60lbs if my memory serves me correctly. I weighed them before putting two of them in my old tinner  

 

 

 

 

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I must have big batteries. It's nice to have speed. I always say when it comes to MPH,  "Hurry up and stop." It isn't very often that water conditions are such that we can go WOT anyway, at least here on Lake Erie. Current will affect boat speed, drastically in some cases especially on The Great Lakes and all rivers. Have you thought about current? When I bought my boat used the original owner could not urge me enough to not go WOT often. He always ran at 3/4 throttle and saved on fuel as well as maintenance. 

Edited by Old Ironmaker

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18 hours ago, lew said:

Just curious, did you have an aluminum prop 1st then switch to stainless and if so, what speeds did you see with the aluminum ?

Hey Lew,   No That is the prop the boat came with .

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That 14x17 prop is a good mid range prop for that set up. The issue is, with your numbers you’re running at about 22% prop slip. I’d buy another prop from a dealer that will let you return it if it doesn’t solve the problem. 
What is your hole shot like?? Does it come up on plane quickly?

 

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