Prop Slip

[LA3]

I am running at 13.5 x 19 ss prop on<br />a C115hp. Pusing an 18.6 Proline CC.<br /><br />The prop does not grab or push boat unless<br />trimmed way in.<br />Once up, from 4,000 rpms to 5,000 rpms, no<br />noticeable speed pick up. Just noise and gas<br />burn.<br /><br />If I turn a half turn, then prop just blows<br />out and slips.<br /><br />Anyone running similiar setup or know where to get RIGHT size prop? Open for suggestions.<br /><br />Thanks

 

[bigbrownbuku]

Re: Prop Slip

your motor is too high on your transom. trim your engine level and run your eye along the plate above the prop. it should be about keel level or slightly lower. if its higher the motor needs to be unbolted and lowered. if its lower check your hull, you may have a hook.

 

[LA3]

Re: Prop Slip

well the engine bracket is on the transom.<br />now where to go lower.<br /><br />I have an older proline and yamaha stepup and<br />it did the same thing.

 

[bigbrownbuku]

Re: Prop Slip

measure the transom height and post here.<br />how did the cav plate line up with the keel?<br />does the transom look like it has an angle more then square with the keel?

 

[LA3]

Re: Prop Slip

Can Plate is just below the keel. Maybe inch.<br />Transom is at 90.<br />Transom height? Inside boat or outside.<br /><br />This is Orignal Setup from Proline.<br />So, it is more prop that boat, engine, etc...

 

[bigbrownbuku]

Re: Prop Slip

whats the history of that prop. is it damaged? has it ever been repaired? make and model?<br />check the hull section just infront of the transom. does it bow or dip at all?<br />is anything mounted in front of the engine at any point along the keel or at the transom?

 

[chanice]

Re: Prop Slip

sounds as if the engine is too high ,a good indication of the correct height is to lower the tilt untill the cavitation plate is at the same slope as the underside of the hull ,look along the cavitation plate from the rear of boat ,when the width of the cavitation plate forms an equal sided triangle with the vee of the hull its about right if not lower the engine.<br /> Also be aware that there is a short shaft version of this engine designed for industrial use, with a different gear ratio, Merc,s also did this with the Mariner, these were used for barge work, so check the clamps to cav plate length on a similar engine !!

 

[Texasmark]

Re: Prop Slip

Transom at 90???????? That says that when you are tucked in all the way the engine is at 90....vertical; anti cav plate parallel with the bottom of the boat.<br /><br />If this is true, no wonder it won't take trim. And even though you are 1" below the bottom (where you shouldn't blow out with that prop) you are still starting out too far out.<br /><br />Normally when you are tucked in the engine is 15 degrees (give or take) inside 90. So after you get out of the hole, you trim out to 90 or so, depending on the situation, and away you go.<br /><br />If you trim out from 90 you are going to blow out unless you are hauling buttox down the lake and if you can't get up to speed to keep from blowing out, you will just blow out, even tucked all the way in.<br /><br />Mark