Unsure if my boat is operating properly, need help

[waterinthefuel]

I purchased this boat about 2 years ago. It' absolutely runs like a clock. Now that I replaced a faulty primer bulb, it starts a lot easier now. It didn't come with a hydrofoil and so I decided to try it without one. Wow, when this thing goes to get on plane, it feels like it goes STRAIGHT UP in the air before planing over. It's almost scary because you can't see ANYTHING when it does that. I decided to check WOT and GPS'ed all I can manage is about 50-52. I'm reading where people, with the same boat and the same engine, are getting 60+ on a GPS. What the heck is going on? Why is this thing a lead sled? It seems to run wonderfully, sounds incredible, but doesn't do anything near 60mph.

I tried putting a hydrofoil on it and while that kept the nose down a bit, it didn't do anything for top speed. I don't know what to do. I have no idea what prop is on it, it's not labeled or anything. It's got that jack plate, I have no idea if its in the right place. I mean it runs flat as can be and seemed fast to me coming from a 13 foot boat with a 28 on it, but apparently its a lead sled.

Any ideas are appreciated.

 

[JoLin]

Couple things you have to check. First, is the motor in good tune? If it needs a tune-up, start there. Second, what does Mariner say that the WOT rpm should be for that motor? Are you reaching it, falling short of it, or running past it? If you can't reach specified rpm, or are going over the specified rpm, you need a different (pitch) prop.

You'll get differing opinions on the usefulness of a hydrofoil vs. trim tabs. I've had both on a small, light boat like yours and I'll take tabs over a whale tail any day. Nauticus Smart Tabs or Bennett SLT's. They're self adjusting tabs and relatively inexpensive. But, you need to get any motor issues resolved before you do anything else.

My .02

 

[fishin98]

Nice boat!....What kind of RPM are you getting when you are trimmed out? Are you sure your throttle is getting your carb's butterflies wide open, are they in sync?
Is your jackplate adjusted so your prop has a full bite. What is the compression on your cylinder's,are they close to or equal? Have you checked that your motor's water pump is pushing enough water through the engine..A over heating engine will not perform. Are you sure your oil injection system is putting enough oil into engine? Are you sure there are no markings for prop pitch...look on the prop body. Lastly..very boater, especially fisherman have been know to stretch the truth on how fast their boat go's. Maybe it's time to spend some BOATING BUCKS and take it to a Certified Marine Technician..not some Back Yard Engineer with Fat Fingers....Just my 2cts

 

[ziggy]

are you using trim properly? googled how to trim your boat
are you using the jack plate properly? googled how to operate a jack plate

along with this.

Couple things you have to check. First, is the motor in good tune? If it needs a tune-up, start there. Second, what does Mariner say that the WOT rpm should be for that motor? Are you reaching it, falling short of it, or running past it? If you can't reach specified rpm, or are going over the specified rpm, you need a different (pitch) prop.

imho wale tales or trim tabs are used to help keep the bow down. that seems counter productive to me for a bass boat that when on plane, rides on the pad with the rest of the boat out of the water. to me, that sounds like it could be dangerous. especially the wale tale. i'd try playing with the trim and jack plate a lot before ever considering add on parts.

to go from plow to plane ya start with trim all the way in. when ya get to plane ya trim out for best possible speed. is that the way your doing it? i don't know about jack plates. some research would be in order i think to be sure your operating that system proper too. trim + a jack plate is a lot of variables.

while this video don't end well. this boat is on the pad and flying. i can't imagine having anything that would try to push the bow down on a boat like this. that boat don't appear to have any tabs or wale tale on it.

 

[waterinthefuel]

I knew someone was going to ask about RPM LOL Thanks for the compliment though, I thought it was a nice boat, and I got it as you see it for 4500. I've never seen another 361V on a tandam axle trailer, all the ones I see are single axle. Truth be known, I didn't look at the tach. It was hauling *** and it's not a huge lake so I was watching where I was going more than anything.

And yes, when I get it up on plane I'm trimming for max speed. The 361V is a very flat running boat. I pretty much can't get the nose up at all when running without porpoising badly, My father has a 150 on a Javelin and he can really trim that thing way up without issues, I can't.

Cylinder compression showed as 120 on all cylinders. All of them exactly the same. It's been tuned up, nothing much to do. I was told mechanically the boat is as close to perfect as a 27 year old boat can be.

The water pump was almost new when I bought it, and it has good pressure and the cylinder temp stays within normal limits while in operation. All the gauges on the boat still work, but the backlights on most of them are burnt LOL

 

[JoLin]

Truth be known, I didn't look at the tach. It was hauling *** and it's not a huge lake so I was watching where I was going more than anything.

Cylinder compression showed as 120 on all cylinders. All of them exactly the same. It's been tuned up, nothing much to do. I was told mechanically the boat is as close to perfect as a 27 year old boat can be.

Until you know your rpm at WOT, and how that compares to Mariner's specs for that motor, you won't know if you can get more speed out of it.

My .02

 

[Scott Danforth]

I decided to check WOT and GPS'ed all I can manage is about 50-52. I'm reading where people, with the same boat and the same engine, are getting 60+ on a GPS. What the heck is going on? Why is this thing a lead sled? It seems to run wonderfully, sounds incredible, but doesn't do anything near 60mph.

are you sure they are accurate? you measured your speed with GPS what did your dash mounted speedo say? guessing it was reading much higher. still need your accurate RPM to know if you truly were at WOT speeds

I tried putting a hydrofoil on it and while that kept the nose down a bit, it didn't do anything for top speed. I don't know what to do. I have no idea what prop is on it, it's not labeled or anything. It's got that jack plate, I have no idea if its in the right place. I mean it runs flat as can be and seemed fast to me coming from a 13 foot boat with a 28 on it, but apparently its a lead sled.

the hydrofoil will slow your top speed down

with trim, jack plate and a proper prop, you should be able to keep the nose flat, and out perform anything a band-aid chunk of plastic bolted to your anti-cav plate could ever do. Since you have no clue to your existing prop and no clue about your RPM, you will need those two pieces of information.

while at it, throw the boat on a scale and verify your not carrying extra water weight from soaked foam in your 27 year old boat

 

[waterinthefuel]

Good ideas there. I didn't put the hydrofoil on it for speed, I did it because the boat goes straight up when planing over and it's dangerous. For 3-4 seconds I can't see ANYTHING in front of me. The hydrofoil does some good. I wasn't real happy with the results as it still goes up.

 

[JASinIL2006]

Sounds like a good candidate for SmartTabs or regular trim tabs.

 

[roscoe]

Some boats will handle differently depending on how the throttle is applied.
trim down.
Try rolling on the throttle slowly till you get up to 7-10 mph, to get the hull moving and start the planing process.
Then go to half or 3/4 throttle.
Experiment.

Sometimes hammer down is not the way to go.

And the bow is gonna rise and block your vision on nearly half of all boats.
If there is something that close, that you need to see and keep your eyes on, you shouldn't be going up on plane until the hazard is cleared.


And you may need to experiment with that jack plate.

Mark it.
Then try raising it an inch at a time.

 

[Silvertip]

It appears the jack plate is set way too high but you need to get back to basics.
1) Find out what the prop diameter and pitch is. Remove the nut and washer. You should see the numbers there or stamped on the hub between the blades.
2) You need to experiment with operation. Trim down for take off, then gradually trim up.
3) Experiment with the jack plate. Whats fine for one operator may not be what you want.
4) Gauges are there for a reason. Look at them. The tach will tell you\ if the engine is in the proper WOT rpm band. Unless you do this you have no idea what's normal.
5) Regardless what boat people have, "theirs" is always a little bit faster but they probably would not put money down in an actual race.
6) Although you say the engine runs fine, some folks can't tell when half the cylinders aren't firing so "verify" the engine is in a good state of tune.
7) Work with the cheap stuff first. Don't though big bucks at a non-problem.

 

[Lowlysubaruguy]

Id like to see a photo or video of the outdrive in the water at speed looking for water line in comparision to the bottom of the boat and the top fin on your drive. To deep not right to shallow also not right if the water line is meeting below the fin you should lower the jack plate. In most cases id think any way. If the fin is below the water line to much youll loose top speed but probably gain more bite theres probably a fine line between the two. Id take what ever tools are required to adjust the jack plate and load the boat they way it would be and tinker with that along with trim. This boat should flatten out prett fast unless you really do have a power loss for some reason.