Top Speed Of Our Boat?

[LuvBoating]

It's a 1992 Celebrity 200 (20') Cuddy w/a 5.7L/350 I/O V-8 engine. In 2012, the block was replaced along with new plugs, alternator, rebuilt (used) carb and all new belts. The boat block now had 25.3 hours on it.

On our local lake here, we've had the speed up to 29 mph. Had the throttle down very close to full speed. If I push the throttle down any further, the engine will start to choke some. Once the throttle is back in the 28-29 mph area, it's a smooth run on plane.

We are down to 1/2 tank of 3-year old marina gas we got when the boat was in northeastern Florida. After our next, and last, trip to the lake this year, we will be filling the tank with 87 octane Sinclair and will be winterized.

What we are wondering is..........should our boat go faster than 28-29 mph or is that about the correct speed?

One other thing, we have two cans of BG44K that we are going to put into the gas tank next Spring after summerization is done by local marine service. The BG44K sure helped our 2005 Dodge Durango a few weeks ago.

 

[Scott Danforth]

there is no mechanic in a can.

is this a 2-barrel or 4-barrel carb?

what RPM are you getting?

what drive ratio do you have?

what prop pitch?

is your speed by GPS or the gauge on the dash?

how heavy is your boat?

BTW, gas doesnt last 3 years prior to going bad. no matter what magic smurf juice you try to add to it. I suggest you get rid of all the fuel in the tank and start with fresh fuel

 

[LuvBoating]

No, there is "no mechanic in a can", but this BG stuff (oil and gas additives) sure work for many, many vehicle owners. And, the boat engine is a 350 Chevy.

The carb is a Rochester 4-barrel.

RPM.........will have too look. Have been only looking at the speedometer and the speedometer is fine. The speedometer was checked with an iPhone speed app.

Drive Ratio: Don't know, mainly because I'm a "computer geek" much more than a marine mechanic. LOL

Prop Pitch is right. Checked it out.

Speed is by gauge on dash, that was checked against an iPhone Speed App.

Boat weight: around 4,000 full of gas.

The tank was completely emptied out in Aug 2017, by our old marine service in Florida. It was then filled at the marina our Dry Storage was at. After they filled it, we only took the boat out once, but started it a number of times on muffs at Dry Storage. The boat was transported here last May 2019, but we didn't move here until August of 2019. After arriving here, didn't have enough time to put it on the water. Had it winterized and it sat (outside) at local Boat/RV Storage. This summer, have had it out three times, trying to get rid of the old gas. Other than the question of speed, the boat has run fine all three times we've been on the water here.

 

[gm280]

There are reason to know what prop you are running and the RPMs at the speed you are topping out at as well and the ratio of gearing. MATH doesn't lie and therefore knowing such things enables us to determine if you have issues to look at... Boat weight, prop pitch, engine RPMs and gear ratio are used to determine such things...

 

[ahicks]

How could you possibly know your prop pitch is right without knowing what rpm you are turning at wide open throttle?

 

[Scott Danforth]

Also, If I recall, you moved from Florida to Denver. if you have not re-jetted your carb, you need to do so.

that 5000' elevation change would drop your boats power output about 15%


pure gas will last 12 months max. pure gas with stabil in it will last 18 months max.

E10 will last about 6 months, E10 with stabil will last about 12 months.

 

[LuvBoating]

Boat weight is listed in my one post. Will get the prop pitch today, by looking at our prop. RPM's: Will get that the next time we go "flying" on the lake. Gear Ratio: Will have to look that up. Really have no idea.

I believe the only "issues" we have to look at is the old gas we have in the tank. May also need to clean out the fuel system and that's why we are going to put two cans of BG44K into the tank next Spring. The former certified auto mechanic that sold us the BG44K Fuel Treatment for our Durango told us that he used the same thing in his old powerboat and it worked fine.

 

[Sprig]

Yes with that engine your boat should go faster than 29 mph. As already stated there are lots of things that affect speed. The first thing you should do is drain that 3 year old gas. Once gas goes bad no additives can make it good again. Additives stabilize gas and make gas last a little longer but won’t fix bad gas. Don’t waste your time and $$ putting an additive in 3 year old. Drain The Tank!!
Since your motor is cutting out at full throttle sounds like you have a carburetor problem in addition to bad gas. Personally I’ve never been a fan of buying rebuilt used carbs. Your fuel filter may be dirty and plugged up. Lots of other things can cause that too.
You say your boat weighs 4000lbs. Are you getting that from printed boat specs or was your boat actually weighed? I’m thinking an almost 30 year old boat may have water in the hull saturating the flotation. That can add tremendous weight to the boat affecting performance.
Also knowing the size and pitch of the prop and the rpm’s at full throttle are of utmost importance.
There are too many variables and unknowns to diagnose the problems here. Provide the information we have asked and we may be able to point you in the right direction.

 

[roffey]

To answer your question, your boat should go faster than 28 MPH. the posters here are trying to find out why your boat is not performing as it should. The boat at wide open throttle should tack between 4600 to 5000 RPM.

 

[ahicks]

Curious about your move too. How did that go? How did you end up moving it?

 

[LuvBoating]

The prop we have on it is a 1916 P19 Quicksilver 3-blade Aluminum. This is the correct one for where we live, as in elevation, etc. We already checked it out, but if anyone thinks we have the wrong prop on, please tell us.

As far as the gas goes, due to the cost of draining the tank, we will just add at least a 1/2 tank of new gas, before having the engine winterized and Storage Gas Treatment added for winterization. We have already used up about a 1/2 tank this summer in three trips out.

The weight of the boat is what is listed in an old website for Celebrity Boat Company.

As far as the Drive Ratio, still working on finding that out.

 

[LuvBoating]

How could you possibly know your prop pitch is right without knowing what rpm you are turning at wide open throttle?

Because when we changed the prop, we put the exact same type on it that we replaced. Actually, a marine service in northeastern Florida bought one for us and put it on.

 

[LuvBoating]

Also, If I recall, you moved from Florida to Denver. if you have not re-jetted your carb, you need to do so.

that 5000' elevation change would drop your boats power output about 15%


pure gas will last 12 months max. pure gas with stabil in it will last 18 months max.

E10 will last about 6 months, E10 with stabil will last about 12 months.

Yes, when the local marine service does the "summerization" on our boat next May, we will also have them do the re-jetting of the carb.

After we had the tank drained of very old gas in August 2017, we filled with marina gas (boat gas) at the Dry Storage we were at in Florida. Stabil was added. Then, in 2018 and 2019 Stabil Storage Fuel Additive was added during winterization. We real feel as if the old gas is slowing down the speed of the boat, but can only afford to replace the gas we are using. Not draining the tank.

 

[PITBoat]

25hrs in 8 years doesn't equal very much use. That in itself is not doing the carb, etc. any good. So yeah, not running 100% now (the full throttle prob and resulting low top speed you mention) even on fresh gas would not be too much of a surprise, I wouldn't think.

I was gonna suggest not filling it up after getting rid of what's in there, one way or another, so you wind up with less old fuel in the future, but that's not gonna solve it really. Starting it regularly as you mentioned is good, but maybe not enough. It's got to be used more, IMO.

 

[Scott Danforth]

Yes, when the local marine service does the "summerization" on our boat next May, we will also have them do the re-jetting of the carb.

After we had the tank drained of very old gas in August 2017, we filled with marina gas (boat gas) at the Dry Storage we were at in Florida. Stabil was added. Then, in 2018 and 2019 Stabil Storage Fuel Additive was added during winterization. We real feel as if the old gas is slowing down the speed of the boat, but can only afford to replace the gas we are using. Not draining the tank.

adding stabil to stabil to stabil on old gas is part of the problem

next year you wont need to worry about draining the tank, you will need to chisel out the goo that will ensue from the fuel going bad.

 

[ahicks]

Because when we changed the prop, we put the exact same type on it that we replaced. Actually, a marine service in northeastern Florida bought one for us and put it on.

So it sounds like you are ASSUMING it had the right prop on it to start with?

If you follow these threads long enough, I think it will be seen pretty clearly a LOT of people did not get the correct prop from the day the boat was purchased new......

At the very least, you should confirm it's the right prop with a tachometer reading at wide open throttle, trimmed out, loaded with an average load. Until you get that tach reading, there is no way on God's green earth you can tell us you have the right prop. You're only hoping you do....

 

[Wxguru]

For reference, our boat, a 1992 Crownline 196BR...so just a tad smaller than yours weighs in at about 4,000 when completely full of fuel, 5 people and gear.
We have a 5.0LX (GM 305), Rochester 4 BBL carb, motor has 331 hours on it now, and have had it up to 40mph (GPS) at around 3800rpm or so, with room to move on the tach/throttle. I imagine my top end speed would be about 47mph with the load we carry. Previous owners have had it up to 52mph with a little more than half a tank of fuel and 3 adults.
That is also with a Mercury 19P 3-blade prop.
Something is going on and you are getting good advice here..keeping hunting the issue.

 

[LuvBoating]

adding stabil to stabil to stabil on old gas is part of the problem

next year you wont need to worry about draining the tank, you will need to chisel out the goo that will ensue from the fuel going bad.

Just to let you know, the Stabil was added to new gas in Florida. This was after the tank was drained of old gas. I should have said the the Stabil Fuel Additive was added only to the new gas. Stabil Storage was added to gas each time we had it winterized in Florida and, last year, here. the "Storage" additive is always added to the gas tank when winterized. Storage Fuel Treatment is different than Star Tron Enzyme Fuel Treatment, of which we have a bottle of now to add when we put the new gas in.

 

[LuvBoating]

So it sounds like you are ASSUMING it had the right prop on it to start with?

If you follow these threads long enough, I think it will be seen pretty clearly a LOT of people did not get the correct prop from the day the boat was purchased new......

At the very least, you should confirm it's the right prop with a tachometer reading at wide open throttle, trimmed out, loaded with an average load. Until you get that tach reading, there is no way on God's green earth you can tell us you have the right prop. You're only hoping you do....

Well.........when we have it winterized, or next Spring "summerized", we will ask the marine service if we have the correct prop on.

From what we know, the prop that is on the boat now, is the correct one. A marine mechanic installed it and didn't say a word about it being the wrong prop. We could have the wrong prop on it, but have to rely on a marine mechanic looking at the prop and telling us. The number of the prop that is currently on it is: 1916P19 Quicksilver. If that's not the correct one, then we have to rely on local boat mechanic to tell us that.

 

[Scott Danforth]

Just to let you know, the Stabil was added to new gas in Florida. This was after the tank was drained of old gas. I should have said the the Stabil Fuel Additive was added only to the new gas. Stabil Storage was added to gas each time we had it winterized in Florida and, last year, here. the "Storage" additive is always added to the gas tank when winterized. Storage Fuel Treatment is different than Star Tron Enzyme Fuel Treatment, of which we have a bottle of now to add when we put the new gas in.

if you never run the tank out, your adding stabil to old gas with stabil in it. since you stated your tank is the same fuel since 2017, what you have in the tank is no-longer fuel. come spring, it will most likely turn to sludge/varnish. then the only cure would be to mechanically clean the tank, pulling the pickup tube and AS valve and rebuilding your carb.