Planing? Prop? Performance? Help!

[ckone0814]

I had an older post in the other section that was in need of additional data but I figure I'll just start again here in Props because it's probably where the post belongs.

06 Century 1850 dc w/ Yam 115 4s. We are really struggling with getting the boat to plane. We've hit plane only a few times successfully but we seem to be unable to duplicate it again under the same conditions (wind, water, weight and trim, etc). In each case, it took minutes rather than seconds to plane. Boat just seems to really want to squat hard under any thrust. Yesterday we got boat to plane successfully and the one factor that was different was that wives were at the consoles and guys were on bow deck. Even then though, we really had to tilt and carry on over 10 minutes to find the any a sweet spot. Not sure it's a significant fact but the gas tank in this boat is aft and we probably have +/-25 gals in her most of the time.

Yamaha perfomance data bulletin had this exact combo @ 38 mph @ 6100 rpms, 4.3 secs to plane, 13 X 17 steel prop, motor mount height #2, with 3538 lbs weight as tested. That's no speed demon and she should probably be fitted with a 150 but if we could do 38 in 4.3 secs we'd be happy. Our set-up is almost the same; same prop and mounting height and maybe a 150 lbs more of weight, 3700 lbs +/-.

When we've successfully been able to get on plane we run about 30 mph (gps) @ 5800 rpms. With just two guys on board (loss of 280 lbs) we see the same results.

From stop to wot, motor tilt full down, the boat squats hard and struggles to reach 4k rpms. There's a big swale of water high behind the boat and you can really hear the motor working; bow is up. As we tilt up it maybe 1/4 dial it does not seem to do much immediately, maybe over 2-3 minutes as we build momentum, but definitely minutes rather than seconds. We wait 30 seconds, then maybe another 1/4, with same results.

So after all that I'm now not sure what I'm looking for from anyone here. Just any advice, questions, experience, or whatever else. We are fully aware that this may be due to operator issues so if you think it is, fire away. Thanks to all!

 

[steelespike]

Re: Planing? Prop? Performance? Help!

A couple of things.Be sure it is running on all cylinders,check the compression the throttle is opening all the way.Is the bottom clean?
It's possible the boat has absorbed water in the foam inder the floor.
this can add a couple of hundred lbs right at the stern where it does the most damage.You could weigh the boat or carefully use a hole saw to open a couple of holes to check the foam.BE CAREFUL you only need to go through
the floor.If the foam is soaked about the only cure is to remove it and replace with new.

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

Is the bottom clean?
It's possible the boat has absorbed water in the foam inder the floor.
this can add a couple of hundred lbs right at the stern where it does the most damage.You could weigh the boat or carefully use a hole saw to open a couple of holes to check the foam.BE CAREFUL you only need to go through
the floor.If the foam is soaked about the only cure is to remove it and replace with new.

Bottom is clean, but it is painted. I guess paint would increase drag?

Please give more details on the soaked foam.

Boat is a 2006 with 40 hrs but I guess anything is possible.

 

[72SideWinderSS]

Re: Planing? Prop? Performance? Help!

Yamaha perfomance data bulletin had this exact combo @ 38 mph @ 6100 rpms, 4.3 secs to plane, 13 X 17 steel prop, motor mount height #2, with 3538 lbs weight as tested. That's no speed demon and she should probably be fitted with a 150 but if we could do 38 in 4.3 secs we'd be happy. Our set-up is almost the same; same prop and mounting height and maybe a 150 lbs more of weight, 3700 lbs +/-.

From stop to wot, motor tilt full down, the boat squats hard and struggles to reach 4k rpms. There's a big swale of water high behind the boat and you can really hear the motor working; bow is up. As we tilt up it maybe 1/4 dial it does not seem to do much immediately, maybe over 2-3 minutes as we build momentum, but definitely minutes rather than seconds. We wait 30 seconds, then maybe another 1/4, with same results.

So after all that I'm now not sure what I'm looking for from anyone here. Just any advice, questions, experience, or whatever else. We are fully aware that this may be due to operator issues so if you think it is, fire away. Thanks to all!

Are you trimming up before you reach plane?

If so that could be your problem.

1) Trim full down before takeoff.
2) Apply Full Throttle.
3) After reaching plane, Begin the trimming process.
4) Adjust throttle for cruising or for ...
5) Readjust trim if needed.

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

Are you trimming up before you reach plane?

If so that could be your problem.

1) Trim full down before takeoff.
2) Apply Full Throttle.
3) After reaching plane, Begin the trimming process.
4) Adjust throttle for cruising or for ...
5) Readjust trim if needed.

I'm not sure we'd ever get on plane at all. Stern just plows, bow is up.

I'm confused by #4 above... why trim if you're on plane already?

We plan on having boat weighed this week. It will be on trailer but we should be able to get a pretty good idea where we're at. We're also gonna get the engine looked at, compressions done, etc.

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

ok so I've been doing some reading on getting on plane and trimming and here's where the issue is. With trim in/down and at full throttle we never get on plane (if we do it takes a long time). The stern stays down and the boat does not seem to want to go faster than 10 mph. At this point I gotta wonder if the motor isn't running all-out or there's too much weight in the stern - Man, I'm really hoping the hull isn't water logged

 

[72SideWinderSS]

Re: Planing? Prop? Performance? Help!

I'm not sure we'd ever get on plane at all. Stern just plows, bow is up.

I'm confused by #4 above... why trim if you're on plane already?

We plan on having boat weighed this week. It will be on trailer but we should be able to get a pretty good idea where we're at. We're also gonna get the engine looked at, compressions done, etc.

This is a very good plan. Do this first, and while it is at the shop, see my remark below.

ok so I've been doing some reading on getting on plane and trimming and here's where the issue is. With trim in/down and at full throttle we never get on plane (if we do it takes a long time). The stern stays down and the boat does not seem to want to go faster than 10 mph. At this point I gotta wonder if the motor isn't running all-out or there's too much weight in the stern - Man, I'm really hoping the hull isn't water logged

Have you checked the trim gauge is actually showing the proper relationship, i.e. when the trim gauge indicates down/in the motor is actually down/in. Did the trim gauge come with the motor?

 

[hwsiii]

Re: Planing? Prop? Performance? Help!

Ckone, if the boat is not water logged, or the bottom is not warped from being placed on the wrong trailer or supports for extended periods of time then there is a very good chance that this boat is very stern heavy, especially with that 4 stroke you have on it and the fuel in the stern. And one of the reasons I say this is because you said that with the men on the bow and the women at the console you got it to plane.You don't say which prop you are using for this setup, please give the manufacturer and the model number as well as the Diameter and Pitch of the prop. I did look for the performance bulletin you talked about and I couldn't find it, could you please give me a link to it.
If you happen to be using the 13" x 17" Painted steel semi cleaver prop, that could be a problem as that prop is designed to run real close to the suface of the water and it has veryyy litlle blade surface area and has some bow lift in it. What you need is a stern lift prop, not a bow lift with all that weight in the stern as well as if you are using the semi cleaver you need much more surface area to make that boat come out of the hole with that weight. I have a friend that has an 18' boat with a weight of 1700 pounds with a 70 HP yamaha running the 13" x 17" Painted steel at 37 MPH. But he doesn't have the weight and especially at the stern to push up on top of the water that you have.
Please tell us what prop and check the bottom of the boat with a straight edge and let us know if you find any sunken spots that are not level on the aft 6' of the boat.

H

 

[11rufus11]

Re: Planing? Prop? Performance? Help!

Did you just buy the boat? If not, has it had this planing problem before or has it just started?

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

Have you checked the trim gauge is actually showing the proper relationship, i.e. when the trim gauge indicates down/in the motor is actually down/in. Did the trim gauge come with the motor?

Yes, the motor and gauge are in sync.

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

Ckone, if the boat is not water logged, or the bottom is not warped from being placed on the wrong trailer or supports for extended periods of time then there is a very good chance that this boat is very stern heavy, especially with that 4 stroke you have on it and the fuel in the stern. And one of the reasons I say this is because you said that with the men on the bow and the women at the console you got it to plane.You don't say which prop you are using for this setup, please give the manufacturer and the model number as well as the Diameter and Pitch of the prop. I did look for the performance bulletin you talked about and I couldn't find it, could you please give me a link to it.
If you happen to be using the 13" x 17" Painted steel semi cleaver prop, that could be a problem as that prop is designed to run real close to the suface of the water and it has veryyy litlle blade surface area and has some bow lift in it. What you need is a stern lift prop, not a bow lift with all that weight in the stern as well as if you are using the semi cleaver you need much more surface area to make that boat come out of the hole with that weight. I have a friend that has an 18' boat with a weight of 1700 pounds with a 70 HP yamaha running the 13" x 17" Painted steel at 37 MPH. But he doesn't have the weight and especially at the stern to push up on top of the water that you have.
Please tell us what prop and check the bottom of the boat with a straight edge and let us know if you find any sunken spots that are not level on the aft 6' of the boat.

H

We bought the boat used in November 08 from a dealer who had it since Spring 08 so we know little about it's history other than that we *assume* by the bottom paint that it spent most of it's one or two seasons in the water. Whomever had it cared for it well - it's immaculate. This season is our first running it.

It's been sitting on a Venture bunk trailer since we had it. It seems supported well aft. The keel only rests on the winch roller, it does not hit the trailer's keel support lower down.

The prop is the oem 13x17 black steel prop.

http://www.yamaha-motor.com/assets/...e_midthrustjetport_bss_cen-1850dc-f115txr.pdf

Thanks.

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

I'd just like to say THANKS to all who've answered and offered help. I'm finding that the boating community are good people - as long as you are courteous and friendly, are willing to learn and listen, and try to do the right things.

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

Been reading about Smart Tabs - could they be our answer? Assuming motor checks out, that is.

Our local Yami service says he's pretty sure hull moisture is not an issue - he saw it in November. Also thinks the 13x17 prop is fine but maybe try 15.

Anyone know when Yamaha lists prop as "black steel" is that literal, black and steel, or could it mean black painted stainless steel?

 

[steelespike]

Re: Planing? Prop? Performance? Help!

If its stainless it will react to some degree to a magnet.Aluminum doesn't.
You could have a dead cylinder and not be able to tell except for the lack of power.Could be as simple as a plug wire off.

 

[hwsiii]

Re: Planing? Prop? Performance? Help!

Ckone, it means it is a semi cleaver prop with very little blade surface area. Smart Tabs are excellent for helping lift stern heavy boats and very cheap to boot. If I were you I would purchase a set, I have tnem and love them.

H

 

[11rufus11]

Re: Planing? Prop? Performance? Help!

Your prop is a stainless prop painted black. Anyway, a four blade prop may help. I am not very familiar with 4 blade props, but I have heard they improve hole shot and faster planing. Don't take my word for it nor go out and buy one tomorrow. Ask around. Just food for thought. See if there is a shop who would let you try one out. Once you finally do get up to plane, your rpms at wot look good. Trim tabs might be a good idea, too. I don't have any personal experience with them, but maybe someone here does and could comment. If your outboard motor checks out, as it should being only a couple years old, the only issue I can think of is the weight of your boat. 3500+ pounds of mass is not too easy for a 115hp outboard to get up to plane very quickly or easily. I have a 115 hp Johnson on my boat, but dry weight is 1350 lbs and, a wild guess here, the total weight with four passengers, gas, and gear is around 2600 lbs tops. I do not have any planing issues, but another 1000 lbs could present a problem. That may be the reason that Century was traded back to the dealer. A 150 hp is better suited for that boat.

 

[Tail_Gunner]

Re: Planing? Prop? Performance? Help!

Been reading about Smart Tabs - could they be our answer? Assuming motor checks out, that is.

Our local Yami service says he's pretty sure hull moisture is not an issue - he saw it in November. Also thinks the 13x17 prop is fine but maybe try 15.

Anyone know when Yamaha lists prop as "black steel" is that literal, black and steel, or could it mean black painted stainless steel?

Let's make this simple...plz post a pic of your boat with the motor all the way down. Try to get a straight on shot that show's just how far below your prop is under the hull.

I assume your have power trim..

 

[MikDee]

Re: Planing? Prop? Performance? Help!

Just a quick question is the cavitation plate (the plate just above the prop) flush with the bottom of the boat? Or up to an inch higher? If not there's too much leg in the water, that could be your problem. Also, If you don't have power trim, put the long trim bolt in the hole that brings the plate parallel with the bottom of the boat for normal operation.

 

[ckone0814]

Re: Planing? Prop? Performance? Help!

the only issue I can think of is the weight of your boat. 3500+ pounds of mass is not too easy for a 115hp outboard to get up to plane very quickly or easily. That may be the reason that Century was traded back to the dealer. A 150 hp is better suited for that boat.

My thoughts exactly but it's kinda funny that the 2009 version of this boat is basically identical and still comes with 115 std and 150 option. Plus, Century is a Yamaha company so you'd *think* they'd pair 'em right, right? Also, the Yamaha performance sheet shows decent numbers - or at least numbers we were ok with.

 

[freddyray21]

Re: Planing? Prop? Performance? Help!

boats are generally sold with the lowest horse power motor for pricing purposes. At 3500 lbs that is a lot of boat for a 115 hp. I've got a 1972 SRV 180 which weighs 1800 lbs and I am running a 120 which is the lowest rating for that boat. I plane fine, but I also have smart tabs. most likely traded in because it was not enough motor for the last owner. The fact that it planed with two in the front tells me smart tabs will help, but you will still be under powered.