test run issues

[rcl700]

I took my pontoon out for a test run yesterday. I had a few issues.

1) I had a new prop on the motor after rebuilding the lower unit. I think I picked the wrong prop . My max RPM was 4500 and I need 5500. I did get 26.6 MPH from my gps unit think I need togo from a 15p to a 13p to get in the torque band .

2) The back of the toon was sitting very low after adding the weight of the motor and gas tank.

3) Water was soaking and splashing and spraying up on the gas tank, batteries, and whole back of the toons.
(do you think raising the motor a bolt hole or two could help with this? ) i have posted a pic of how low the foot hangs below the transom.

[lakerunner]

I would raise it till lower cavitation plate is even or close to even to the bottom of transom

[slingshot]

More info on your boat would help because those with the same or near identical setup could chime in with more accurate setup into:

1.) Sounds like your over propped. For every inch of pitch you go down on your prop you will grain about 200 RPM on your engine at WOT. Before you do this I'd make sure your engine is running well by doing a good tune up.

2.) yes, most toons will have a low stern once motor and tank are put on (normal). Crest makes a "Tappertoon" which makes the boat more even when at a stand still by tappering both toons from 26" dia at the stern down to 24" at the bow.

3.) Normal, my tank partially sits in the water because Crest puts it in the engine pod. My batteries would get soaked if they weren't enclosed. The back of my boat is under constand splash when at speed. Your battery is in a battery box so your good to go.

[rcl700]

Ok I don't know the manuf. of my pontoon it says bandit on the side. It is 20ft
the boat is currenty unloaded. It has a console and one flip flop seat ( so it's on the light side) my motor is a tohatsu 90hp the prop I was testing with was a 13-3/4" 15p prop.
It got to 4500 Rpm. My motor needs 5200-5800 Rpm. / test was made with two people in the boat.

I'm thinking on trying a 14" 13p prop. ( do you think this will get me where I need to be? )

I got 26.6 mph at 4500 rpm. What do you think I will get with the correct prop?

If water is splashing over the tank will it get in by way of the vent?

Will raising the motor one or two bolt holes change performance? If so how?

[Parasympathetic]

I would get the motor mounted correctly then work on fine tuning your prop selection.
do like lakerunner says and move the motor up and get the cavitation plate even or close to even with the bottom of the transom.

[slingshot]

I don't think you have a motor mount issue. From your photo's it would appear that you have no splash deflector of any kind which many manufacturers put around the transom which would explain the splashing. If you’re happy with your engine's performance, I think going down in pitch is a good idea. Many marine shops will take a prop back as long as it's undamaged and returned in a couple of days so you can get the engine RPM's right were you want’em.

If you go down in pitch expect a small increase in top end (1 or 2 mph) given where you’re RPM's are now and where you want to be. The big performance you'll notice is a better hole shot and acceleration. However, you mention you're increasing diameter which will actually lower RPM's at WOT thus, countering your attempt to get to your 5500. I would try the 14 X 13 but have a 14 X 12 on hand to give it a try.

Gas tank issue, can’t answer to that except that it doesn't make sense that a marine gas tank manufacturer would create a tank that when splashed would allow water in the tank. That having been said, a water fuel separator is always a good idea.

If you raise the motor you will decrease drag (good thing) you'll also lesson prop grip and cause cavitation if raised to high (bad thing). Of course the idea would be to get it at the cusp where you get the least drag with the most grip as possible.

[Parasympathetic]

Slingshot apparently likes his mounted lower than the rest of the world. Again, looking at the pics, yours is mounted too low. Swing by any boat place that sells boats or pontoons and ask them the proper height.

you may have a splash shield issue also as slingshot said, but if you don't get the height right, you'll need a splash shield 8 foot high to stop all the water.

[bruuuuce]

Landau made a boat named "Bandit"

[slingshot]

Raise your motor or not I'd be curious what your final set up is (I won't speak for the rest of the world). let us know.

[rcl700]

Ya I was thinking Landau also.
I wonder if I could call them and check the ID # with them
then I could have more info on my boat.

[Parasympathetic]

I had another post here that apparently got deleted.......and it wasn't even bad. I posted, watched it show up, and matter of fact, it showed up on a SECOND page that is not here now underneath someone elses post. What's up wid dat?

Herb, you slashin and burning again?

[WaltF]

Apparently Herb fell asleep at the helm....

Herb....oh heeeerb....

[badmoonrising]

Admin log says nothing was recently deleted...

[WaltF]

I havent seen anything deleted cept when some moron spammer trying to sell something shows up...
These mods let most anything stand, unlike that 'other' place...

[dahogman]

I had a 2005 G3 LX20 F/C it had U shaped toons on it also and was a 20 footer. I also had a 90 Yamaha 4 stroke and was propped identical to you. I can tell you without a doubt that your motor is to low. Raise the motor until the cav plate is even with the bottom of the transom. Raise the motor first, the splashing is coming from the motor being to far in the water and its creating drag=splashing. I've been down this road, raise the motor and most of the splashing will quiet down, Rpm's will come up due to decreased drag, speed will also increase. I'll see if I can find a pic of mine.

motor to low.jpg (21.89 KiB) Viewed 6629 times