Motor mount height

MercFan

Petty Officer 1st Class
Joined
Dec 31, 2005
Messages
347
Hi guys!<br /><br />Had a great week-end at the dam thanx to all the advice gathered here!<br /><br />Motor is running good, but it's over propped at this stage :( Running a '70 1150 on a 18 foot deep V hull Bowrider (9 seater if you load up the people) I'm only getting 4800 rpm at WOT on a 17 Pitch prop. The prop diameter iirc is 13,75 or 13,5. I believe I need a 15 in. pitch.<br /><br />The other that's bothering is the motor height. I have to trim all over the place when pulling away, planing and cornering. I'd love some input on this:<br /><br />Looking at the hull from the rear, where do I measure from? The theoretical intersection of the 2 V lines? Or the actual little flat spot right at the bottom (the keel I believe).<br /><br />Then, where do I measure to? The ridge that runs right above the prop and just below the gearbox oil level plug?<br /><br />And lastly, should the plate be above or below the keel, and most importantly, by how much?<br /><br />Thanks in advance!
 

Rovernaut

Petty Officer 2nd Class
Joined
Jun 15, 2005
Messages
116
Re: Motor mount height

I believe the captivation plate on the leg should be inline with the bottom of the hull, so that you don't get air bubbles from the hull causing captivation.<br />Sometimes and inch up or down might be needed.
 

MercFan

Petty Officer 1st Class
Joined
Dec 31, 2005
Messages
347
Re: Motor mount height

Thanks Rover!<br /><br />I'll take accurate measurements tonight and see where I stand. I'm also looking at venting the prop as per other post here in the forums.
 
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