need more power!!! advice please!!!!!

[tron9123]

this is my baby! shes a 19.5ft 1974 bayliner liberty. i got her at the start of last summer for what i feel is a great deal cause she runs like a top $3500. The floors and stringers are new along with her power. the problem im having is she is a big old heavy girl and the people who owned her before i re-powered her with a 2006 mercuiser 3.0/alpha one 135hp(great shape/great motor}. the boat gets up out of the water 90% of the time the problem is add some chop and she just cant get up,just plows water. I was thinking adding tabs, maybe changing the prop .I know nothing about props and pitch not even sure whats on it now but please and help at all is more then welcome

cheers

Troy

oh and ps i googled my boat and some models did come with a 4 banger kinda just fyi

 

[alldodge]

Re: need more power!!! advice please!!!!!

:welcome: to iboats Troy

Do you know what rpm you are turning at WOT in smooth water?
If not find a hand held tach and let us know.
Does the trim work on the outdrive?

 

[steelespike]

Re: need more power!!! advice please!!!!!

The Liberty in 79 was 120 hp, at 20ft and 2700 lbs.so your golden with a 135.
We need more info, the prop size should be near the base of the blades or under the prop nut.
Need your lightly loaded wot rpm and gps speed.Look on the out drive for the gear ratio.
It's probably has a stern bias when you start adding weight unless you can find some to ride in or on the bow.
Very likely a prop change will help you out.

 

[hwsiii]

Re: need more power!!! advice please!!!!!

Troy, I show the Liberty to have had a dry bare hull weight of about 2,800 pounds with a 120 HP 4 banger when it was new. Assuming that is close to what it weighs now she is a heavy old girl, even for the new motor.

Did you also install the new outdrive as well, or just the motor.

Before you add trim tabs lets see what changing props can do to help you.

We need to know Exactly what make and model of prop as well as the diameter and pitch, having the wrong prop can very easily create these problems, especially when you combine minimal horse power as well.

How many people and how much gas and gear are on the boat when you can not get it on a plane.

And then we need to know what maximum speed you are able to attain with that load at what RPM's. With that information we will be able to help you.

H

 

[tron9123]

Re: need more power!!! advice please!!!!!

The Liberty in 79 was 120 hp, at 20ft and 2700 lbs.so your golden with a 135.
We need more info, the prop size should be near the base of the blades or under the prop nut.
Need your lightly loaded wot rpm and gps speed.Look on the out drive for the gear ratio.
It's probably has a stern bias when you start adding weight unless you can find some to ride in or on the bow.
Very likely a prop change will help you out.

the prop reads 48 78118 a40 17p i see nothing for gear ratio on the out drive but it is also newer matching year of the motor. cant say my wot/speed/rpm till i take her out again but i will for sure get that info.

Ruff guess is on plane around 25mph at between 3500-3800. when she gets up all feels great sits nice and high in the water and doesnt skip a beat, The problem seems to be getting up. when i cant get up its bow right up 3200 rpm is all she will rev to and does 5ish mph plowing water.

it has twin tank in the stern that hold 100 liters of gas so around 26.5 gallons so it should be stern heavy but full or 1/4 tank left doesnt seem to make a difference.


thanks for helping

troy

 

[tron9123]

Re: need more power!!! advice please!!!!!

Troy, I show the Liberty to have had a dry bare hull weight of about 2,800 pounds with a 120 HP 4 banger when it was new. Assuming that is close to what it weighs now she is a heavy old girl, even for the new motor.

Did you also install the new outdrive as well, or just the motor.

Before you add trim tabs lets see what changing props can do to help you.

We need to know Exactly what make and model of prop as well as the diameter and pitch, having the wrong prop can very easily create these problems, especially when you combine minimal horse power as well.

How many people and how much gas and gear are on the boat when you can not get it on a plane.

And then we need to know what maximum speed you are able to attain with that load at what RPM's. With that information we will be able to help you.

H

the prop reads 48 78118 a40 17p i see nothing for gear ratio on the out drive but it is also newer matching year of the motor. cant say my wot/speed/rpm till i take her out again but i will for sure get that info.

Ruff guess is on plane around 25mph at between 3500-3800. when she gets up all feels great sits nice and high in the water and doesnt skip a beat, The problem seems to be getting up. when i cant get up its bow right up 3200 rpm is all she will rev to and does 5ish mph plowing water.

it has twin tank in the stern that hold 100 liters of gas so around 26.5 gallons so it should be stern heavy but full or 1/4 tank left doesnt seem to make a difference.

as for the people it has been as little as me and the girlfriend my dog and the standard cooler and safety gear id say 450 lb in total.


thanks for helping

troy

 

[explorer 542]

Re: need more power!!! advice please!!!!!

I have a 2005 19.6 foot Campion explorer 542 with a 115 hp 4 stroke outboard mercury she looks a lot like your boat. I was having the same problems if I added some weight and fuel she wouldn't plane and i was getting really disappointed since this was our first summer with this boat. I realize that my outboard runs at a higher rpm then your I/b but going from a 3 blade 15 pitch prop to a 4 blade 13 pitch prop solved all my problems my boat will now plane in under 5 seconds no matter of weight and has a top end speed of 35 mph all good stuff. I feel that if your engine is running right all you have to do is talk to your local prop guy find out your WOT for your engine and when you find the right prop for your boat you will be more then happy with the results.

 

[Rick Stephens]

Re: need more power!!! advice please!!!!!

I have the same motor in a 17 foot deep V that is probably 600 pound lighter boat. Using the same 17 inch pitch Merc prop as yours it planes up at 2400-2500 RPM in the high teens MPH. I mostly run a 15 inch pitch 4 blade that planes up nearer 2000 RPM. No trim tabs on it.

Just as a guess, without knowing your RPMs and speeds, I would bet you need to go quite a bit lower in pitch for the weight. It will be obvious if your RPM won't smoothly run up around 4500 at WOT. If your motor is staying in the high 3k or even in the low 4k range you're lugging. Hard on the motor as well as hard to plane.
Rick

 

[steelespike]

Re: need more power!!! advice please!!!!!

While 135 isn't ideal;I think it should react normally if a little sluggishly with a 17" prop.I've seen any number of
reports of 19 footers loaded with people and gear pulling skiers with a 3.0 and 17" prop.
And the 19' might over rev with a light load.
Granted probably a little lighter than your boat but pulling a skier is impressive.
Don't assume because its a "new" installation that everything is right.Be sure the throttle opens all the way,
While its probably electronic ignition be sure the timing is set right and advances as it should.
You might do a compression check. Do you trim down for hole shot and does it go down all the way?
It's my feeling a 135 should make 30-35 with a light load, you,girlfriend and dog.

 

[Scott Danforth]

Re: need more power!!! advice please!!!!!

Going to jump in here

Agree with the prior question by steelespike on the throttle - is it opening up all the way?

I will re-iterate the first question by AllDodge: What RPM are you running at WOT?

Now assuming that your throttle plates do open all the way at full throttle, and assuming you are getting 4500-4600 RPM at WOT on calm water...

First question I have is operational: Are you trimming all the way down for the hole shot? That is a must on most 3 liter boats. Trim it all the way down, mash the throttle, then when it comes up to plane, trim up to the sweet spot. In calm water, you can briskly roll into the throttle

If you are, then try putting your cooler with beer in the front bow area, or have someone sit up there when you do the hole shot. If that works, you can do that every time, or drop to a 15 pitch prop from your 17 and watch your top end RPM at cruise.

Now assuming that your highest RPM is the 3500-3800 RPM you mentioned in your posts, you have either the wrong outdrive gear ratio or something else is wrong like the boat has 1000# of wet foam. With the right gear ratio and with boats of similar size and weight as yours originally, you should be able to get out of the hole every time and cruise about 35ish.

to verify your outdrive gear ratio, turn the engine around 10 times by hand with the drive in gear, and have someone count the revolutions of the propeller

For reference, I hit 41 with my old 17' boat with a 3.0 and I had 2 coolers of beer, a bunch of fishing gear, 4 svelte guys at about 230# a piece and in a 2' chop using a 19 pitch prop. I could ski with 6 people on board with the 17 pitch, however to get the skier and boat out of the hole, I had the 3 heaviest people in the bow. It wasnt the fastest out of the hole, but it would do it every time

 

[tron9123]

Re: need more power!!! advice please!!!!!

It does trim all the way and I have it fully down on the hole shot, I play with the trim when it's not getting on plane doesn't seem to make a difference. I will check the throttle and god I hope the compression is good. I feel the same 135 isn't idea I but I should be getting more out of her. I think pitch change is first.

Thanks for the help

Troy

 

[Scott Danforth]

Re: need more power!!! advice please!!!!!

what RPM are you hitting for RPM at WOT?

 

[smokeonthewater]

Re: need more power!!! advice please!!!!!

:welcome: to iboats Troy

Do you know what rpm you are turning at WOT in smooth water?..............

..........we need to know what maximum speed you are able to attain with that load at what RPM's. With that information we will be able to help you.

H

..........I will re-iterate the first question by AllDodge: What RPM are you running at WOT?...........

what RPM are you hitting for RPM at WOT?

By this point you should be figuring out that unless you tell us what rpm the engine hits when you are up on plane at WOT (Full throttle) going as fast as the boat can go then we can't help you.

We NEED that info to continue

Another angle... you mention that the problem occurs "in a chop"... Is it possible that you are taking on water in said chop?