Propping correctly & how to test props.....

We just had this discussion with a customer who has a 2859 Bayliner diesel. WOT RPM should be around 3600, and his boat tops out at 3000 RPM. He says he knows, but since he never runs at WOT throttle it's okay. Since he cruises at onlt 2000 RPM he feels he's fine.

No amount of discussion woudl disuade him, and he used to work at one of the large marine retailers, so you would think he would know better. His answer was that he understood, but that he know better.

All we could do was shrug and wish him well.
 
Regarding the engine height - We had repowered our new to us 22 last winter. The Honda 90 was mounted all the way down. It never felt right, sluggish and the permatrim was making an awful side spray. At the end of the season we pulled it from the slip brought it home and raised the engine just one bolt hole. Wow! It feels like a different boat. Faster, more responsive and the permatrim really does its job.

Most of you already know this… If you are moving a Honda 90 up from the lowest setting, if not already done you will need to trim the black transom cap on the back side. We got everything bolted back in place and realized the motor now hit the ledge on the back of the transom cap and the motor would not mount flush. We had to swing out the motor and trim the cap off with a router. I think they do this at the factory on the newer boats.

Kevin
 
I really agree with the comment on how manufacturers and dealers rig most motors. I have looked at 9 different new motor installations and only one was mounted at the correct height. All the others were buried. The 25 I bought used had the motor buried and it had been run that way for 4 years. It's amazing what raising the motor does for performance and economy.
 
I agree that engine height and proper prop selection is very important to boat performance. I'm not an expert by any means, but know this: you can also create challenges by mounting your engine too high. I think the "extended ruler" rule of thumb might still be a pretty good guide for most of us. The hulls on the classic C-dories are flat, whereas most other common boats have varying degrees of deadrise. You can probably get away with higher mounting on a v-hull boat. New engine mounted too high in my case caused very annoying porpoising problems and cavitation of the prop during turns. Called Les and got the skinny on how to correct this issue: "drop the engine down a hole and set the plate bottom flush with the hull bottom". I also agree that the process of correct prop selection is worth the effort in terms of performance and engine life. Thanks again to Les, Matt, and Marc for their participation and input on this site and privately Mike.
 
I have an 115HP Suzuki and was wondering if this raising the Engine Project can be done by a owner without too much trouble and or a lift? Or is this a take it to the Boat Yard project?
I have an issue where my Permatrim does not really drive my bow down and I need to use ¾ trim tabs to get her full bow down and running at top speed. I also get a funny wake and or splash out back. As the boat is out of the water for the season, I can’t do the cavitations plate check now, but just want to know what I am in for if it turns out I want to raise the motor.

Thanks Jim
 
Jim, I think you could DIY if you had a hoist that would support the weight of the engine. After all, you don't need to disconnect anything, just unbolt the 4 bolts and rebolt it one hole higher. (I think). Those 115's are heavy though, I thought about doing it on my 115 Suzis to get to the T/T motors to do some work but had my marina guy do it instead. You actually have to REMOVE the stbd engine mount to get to that mechanism.

Charlie
 
Jim - Yes, as Charlie said, you need a lift. I took mine to a local shop and it was less than an hour of their time with me helping. My Honda takes a special fitting that screws in the top of the motor for the hoist to clamp to, they have the fitting. It was well worth the cost to have the right tools for the job.

Kevin
 
Thanks Guys, You have convinced me that this is not a DIY, as I don't have a lift and don't know what issues and or tools I may run into. I'll leave it to the professionals, once I determine, I should have it raised.

Have a great weekend.

Jim
 
A Fishin C":pekftlx4 said:
permatrim - will it decrease or increase ventilation?
Click to expand...

We had a ventilation problem & unless we were somewhat heavy in the stern would have to trim the motors all the way down to prevent it.   The Permatrims stopped this completely & can now do tight turns at speed even with the trim tabs forcing the bow down & the Permitrims aligned with the bottom of the boat.   On the other hand they come with the cost of a couple hundred rpm & one or two mph on the top end which was well worth it to me.

Jay
 
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