Prop / Motor Position (check the pic)

[studlymandingo]

Okay, I've been following several of these threads, and I think I need some help here. I have an 18' Center Console with a 1986 Mariner 150, and a 60 gal fuel tank. I recently installed a 14.25 X 21 Rapture SS prop. After reading some on these threads, today I removed the vent plugs and put her in the water for a test run. Previously, the holeshot was less than desirable, and the WOT was a meager 5200 RPM. Today, the holeshot was improved some, and top-end was 5400 RPM. I'm not sure exactly what the WOT difference was other than temperature, it was a good 20 degrees cooler today than 2 days ago on the last run, oh and a can of Sea Foam in the tank. <br /><br />Now, for the motor position part; after reading all of the posts regarding raising up the outboard, I am thinking the motor may be positioned too low. Today while at WOT, I noticed the AV plate was not out of the water. The motor is on the top hole, which means it can be raised significantly. I am going to attempt a photo post here that shows the lower unit relative to the bottom of the boat.

 

[WillyBWright]

Re: Prop / Motor Position (check the pic)

You can usually eyeball it by trimming the motor level with the keel. Then look from the back even with the anit-ventilation plate. For more speed raise it up a hole or two. But realize that the prop may suck air easier on tight turns and in rough water.

 

[studlymandingo]

Re: Prop / Motor Position (check the pic)

Where should the anti-ventilation plate be relative to the bottom of the boat? I can't figure out how to upload a photo, but I took a pretty clear picture of the motor as it is.

 

[Dhadley]

Re: Prop / Motor Position (check the pic)

Height is relative to prop design and hull configuration. Some boats may work best with the AV plate an inch or two up. Some rigs run with the center line of the proshaft even with the bottom. Or slightly above. There is no one set dimension for any given motor on a given boat. Obviously the larger diameter you run the higher you can go.<br /><br />The best advise is to try raising your motor up some and test. From what you're saying I'd bet going up will help. Try to get some GPS speed reading. That'll help in determing slip.

 

[gatorred]

Re: Prop / Motor Position (check the pic)

www.photobucket.com to put pic to link to I haven't figured out how to up load a pic here

 

[Realgun]

Re: Prop / Motor Position (check the pic)

Do a Search. Search<br />look up at top of page in RED and BOLD!<br /><br />In the box look in all open forum and type. "post picture"<br /><br />There are at least 200000000000 posts on how to do this. ok not that many but close.<br /><br />And yes we really want to see what your describing. Some people can even help.

 

[studlymandingo]

Re: Prop / Motor Position (check the pic)

Here is a link to the picture. I can't seem to locate the posting for how to put the actual photo in the thread.

 

[Dhadley]

Re: Prop / Motor Position (check the pic)

OK, trim the motor until the AV plate is parallel and then run a srtaightedge from the plate forward to the hull. From the bottom of the keel to the straightedge is the X dimension. What's that measurement?

 

[studlymandingo]

Re: Prop / Motor Position (check the pic)

 

[studlymandingo]

Re: Prop / Motor Position (check the pic)

Took me a few days to get this one back; weather took a turn for the better. Today I was WOT with 4 adults, a 70LB Dog, 3/4 of a 60 Gal tank of gas. WOT was 5300 GPS says 41.3 m/h. Do I move her up a notch or two???

 

[studlymandingo]

Re: Prop / Motor Position (check the pic)

Today I was out, 2 adults approx 40 gals fuel WOT 5200 RPM 46.1 MPH by the GPS