115 merc 4 stroke on crestliner superhawk 1700

[timdan94]

I have a crestliner superhawk 1700 with a 2008 merc 115 fourstroke on it. I am having problems with the boat getting on plane (it takes a long time) and blowing out when trimming out. I have a black max in both 17 and 19 pitch. They both have the same problem. I was wondering if trying a turning point hustler with the vent holes would help with the hole shot. The engine only has about 2 hrs of run time on it. So I don't know if I should just run the motor more to break it in and see if it loosens up and revs up easier or start playing with props.

Any thoughts?

 

[steelespike]

Re: 115 merc 4 stroke on crestliner superhawk 1700

What is the max rpm and speed with each prop?
Where is the antivent plate,just above the prop, in relation to the bottom of the boat.Measure with a straight edge along next to the keel.
Usually should be about an inch above the bottom.Is there anything installed that might disturb the water near the prop.The Hustler does resist venting very well.

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

What is the max rpm and speed with each prop?
Where is the antivent plate,just above the prop, in relation to the bottom of the boat.Measure with a straight edge along next to the keel.
Usually should be about an inch above the bottom.Is there anything installed that might disturb the water near the prop.The Hustler does resist venting very well.

The anitivent plate is even with the hull. There isn't anything that should be disturbing the water near the prop that I can see. I'm only getting about 40-41 with each prop. I'm only hitting about 5400 rpm with the 19 and about 5800 with the 17. The max rpms for the motor is 6400 rpms.
Thanks.

 

[steelespike]

Re: 115 merc 4 stroke on crestliner superhawk 1700

Propping closer to the max rpm should help hole shot.A 17 should be pretty close to what you need.It seems to me that a 15 is close to extreme.With a 13 just 2" down likely to be used on a pontoon.Obviously a very hard to push boat.You might be sure the throttle opens all the way,bottom is clean and smooth.Motor is in excellent tune.
Actually your speed while slightly low from typical lower speeds in that size boat
It appears to me that speeds above 44-45 would be the exception.By the seat of my pants I do believe your speed is about right for your rpm.
With your venting problem I wonder if a vented prop may cause more venting.?Of course you could plug the holes if venting remained a problem.

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

The engine is EFI. The boat is 1300 lbs, engine 410 lbs, 33 gallons of fuel, plus about 300lbs in anchors, batteries, trolling motor, other gear and about 350lbs of people is my usual load. I was just wondering if the vented prop would help with letting the engine spool up to higher rpms to get on plane better.

 

[steelespike]

Re: 115 merc 4 stroke on crestliner superhawk 1700

So is the rpm you gave us with a full load or just you aboard.While a loaded rpm can help; rpm and speed lightly loaded will tell if the motor is propped to the high end of its rpm rating.Critical with a 4 stroke.I assume you try to balance all that weight.

Your throttle has to open all the way whether efi or carbed.While it isn't likely some times the throttle can be setup wrong on the motor itself or the cable adjustment.Yours wouldn't be the first not right.
Give the vented prop a try worse that will happen is you plug the holes and try again

 

[Silvertip]

Re: 115 merc 4 stroke on crestliner superhawk 1700

I've not done serious testing with vented props on a four stroke but my thoughts are this is not a solution. Two strokes respond well to vented props but four strokes don't seem to benefit as much from the reading I've done. I wouldn't look at that as a priority at this point. With only a few hours on the motor I would certainly break it it before spending money on props. If you've been used to the way two strokes pop a boat on plane, it will take you awhile to get used to the way four strokes operate.

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

So is the rpm you gave us with a full load or just you aboard.While a loaded rpm can help; rpm and speed lightly loaded will tell if the motor is propped to the high end of its rpm rating.Critical with a 4 stroke.I assume you try to balance all that weight.

Your throttle has to open all the way whether efi or carbed.While it isn't likely some times the throttle can be setup wrong on the motor itself or the cable adjustment.Yours wouldn't be the first not right.
Give the vented prop a try worse that will happen is you plug the holes and try again

The rpm is with an average load (the wife, myself, and fishing gear). I try to balance it as best possible. I'll have to figure out how to check and see if the throttle is opening up all the way. I was thinking of trying a vented prop because when I take off the engine hits a wall at something like 3000 rpms then finally gets on plane. Sometimes I trim out when I get to that point and it helps it to plane.

I've not done serious testing with vented props on a four stroke but my thoughts are this is not a solution. Two strokes respond well to vented props but four strokes don't seem to benefit as much from the reading I've done. I wouldn't look at that as a priority at this point. With only a few hours on the motor I would certainly break it it before spending money on props. If you've been used to the way two strokes pop a boat on plane, it will take you awhile to get used to the way four strokes operate.

I'll just have to tell the wife the honey-do list will have to wait and take the boat out tomorrow and just run the hell out of it to get some more time on it. I don't really mind how the 4 stroke gets on plane but I want to get the motor so it will get to recommended rpms, which in this case is 6400. I'm glad I went with the 4 stroke it doesn't use much gas at all. I've thought about smart tabs to help get the boat on plane because it is a heavy boat, the gas tank is towards the back and that 410 lbs of engine hanging on the back doesn't help.

Thank You guys for taking the time to help me. I appreciate it.

 

[mommicked]

Re: 115 merc 4 stroke on crestliner superhawk 1700

what about a 4 blade prop?

 

[briboat]

Re: 115 merc 4 stroke on crestliner superhawk 1700

Using a 4 blade rubex prop 15pitch I spin 6300 rpm on mercury 115 fourstroke with excellent holeshot and holds very well in the water.I too added smart tabs with 60lb actuators and that seem to offset the weight issue.Jumps onto plan,cruise speed is good and porpoising stopped.
2004 FS1700 fiberglass with 2008 Mercury 115efi.
Hopes this helps .
previous mercury 3blade blackmax 17pitch spun 5500rpm.
I would say expect too see 600-800 rpm change if changing pitch

 

[walleyehed]

Re: 115 merc 4 stroke on crestliner superhawk 1700

I would agree on first getting 20-25hrs on your rig. I would also agree possibly with a good 4bld in a 15P. 60lb actuators is too much though on the smart-tabs....40lb would be better. I use 60's on my V6 200+HP on an 18ft Alum deep-V and that's almost too much. I set up 18ft'rs with 115's with 40lb acuators and it leaves room for a good prop to still add bow-lift at WOT.

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

One thing I found out today is that when on plane the anti vent plate is still under water. With 4 people in the boat I'm only getting 5300-5400 rpms with the 13X17 prop.

 

[steelespike]

Re: 115 merc 4 stroke on crestliner superhawk 1700

You could try to raise the motor but if you are having venting now you may not be able to.

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

I'm probably gonna have the marina raise it one hole and see what happens. They told me that we would do what it takes to get that engine to recommended rpms. Including moving the engine height around and playing with props until I'm satisfied.

 

[walleyehed]

Re: 115 merc 4 stroke on crestliner superhawk 1700

Please listen to what I say when I suggest getting 20-25 hrs on your rig first...I've been down this road before as a prop consultant doing set-ups on 4-strokes, which has fooled me many times, especially seeing a 17P so low in rpm on the 115 on that boat.
May I ask what altitude above sea-level you are operating at?
We've been running 17P's on the 1700 with 90hp 4 stroke Mercs' and seeing about 6150-6300 w/eng. in third hole with a good SS. I have not tried to go any higher. But these engines also have all had 40-50hrs + before attempting to fine-tune the set-up.

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

Please listen to what I say when I suggest getting 20-25 hrs on your rig first...I've been down this road before as a prop consultant doing set-ups on 4-strokes, which has fooled me many times, especially seeing a 17P so low in rpm on the 115 on that boat.
May I ask what altitude above sea-level you are operating at?
We've been running 17P's on the 1700 with 90hp 4 stroke Mercs' and seeing about 6150-6300 w/eng. in third hole with a good SS. I have not tried to go any higher. But these engines also have all had 40-50hrs + before attempting to fine-tune the set-up.

Ok I guess I'm expecting too much from such a new engine. I'm just gonna go run the engine and cruise around for a while. I figured since I had someone with me yesterday that knows a little about boats I had them check and see if that plate was under water or not(wife wouldn't do it). They have that motor on the second hole from the top as it is now. I think part of my problem is that I'm trying to trim out too far. My last boat I could trim all the way out and not blow out. I trim out till I hear the engine/prop sound funny then trim back in a little bit. I've never had a new boat so this breaking things in is something new.
Our elevation is about 530ft
Thank you for your help I appreciate it.

 

[walleyehed]

Re: 115 merc 4 stroke on crestliner superhawk 1700

Ok...we can take elevation out of the picture...shouldn't be any loss of power at 530...2000ft-up starts to change things.

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

Please listen to what I say when I suggest getting 20-25 hrs on your rig first...I've been down this road before as a prop consultant doing set-ups on 4-strokes, which has fooled me many times, especially seeing a 17P so low in rpm on the 115 on that boat.
May I ask what altitude above sea-level you are operating at?
We've been running 17P's on the 1700 with 90hp 4 stroke Mercs' and seeing about 6150-6300 w/eng. in third hole with a good SS. I have not tried to go any higher. But these engines also have all had 40-50hrs + before attempting to fine-tune the set-up.

What speeds are they getting with the 90

 

[walleyehed]

Re: 115 merc 4 stroke on crestliner superhawk 1700

I think most are running 43-45 in that range with some differing loads.
The 115 is only showing a strong mph or maybe 1.5 at best, above the 90hp with same prop. The 90 is just a shag slower on hole-shot.
We strapped a 135 2-stroke on one that had a yammy 4-stroke 115 and was still hard-pressed to hit 46 so that tells me the hull is fighting back....against the wall if you will

 

[timdan94]

Re: 115 merc 4 stroke on crestliner superhawk 1700

ok thanks for the information.