Proper engine height

[Crownie2]

Re: Proper engine height

Now that I see the stern - that's exactly it! The tilt n trim is way too low and is probably digging into the water.

Find a way to mount it a couple inches higher, at least, and then remount the engine lower by about the same amount. Failing that use the splash plate (buy or make yourself) mentioned above. It acts sort of like a trim tab but connected directly to the bottom of the unit to keep it from dragging in the water.

And don't forget the the unit is adding extra weight at the stern, which isn't helping the hole shot any.

 

[diaric]

Re: Proper engine height

ok, thanks, makes sense. I'll find a piece of alluminium and make a splash plate. mounting higher will have to wait till the end of the season, as i will have to seal up the mounting holes that are there now. If i bring the tilt up about 2 inchs i can only drop the motot back about 3/4". will try the splashguard with the hydrofoil back on 1st and see what that does. when i remount higher do u think i should shim it so the motor is tucked in more at the same time?

 

[Crownie2]

Re: Proper engine height

Good plan. You may find that The splash guard makes enough difference.

From what I can see - it LOOKS like with the hydrofoil on there your trim in should be OK the way it is.

Do you need that piece of plywood in there?

Also - I would call CMC and discuss all of this with them - I am sure they would be willing to help you.

Bob

 

[diaric]

Re: Proper engine height

i emailed cmc and they don't make a splashguard. The piece of plywood was to shim it up a little higher. I will try later with it out so motor down 3/4" more. raided the neibours junkpile and made a splashguard out of an old bug deflector, alluminium lip and plexiglass. it comes back about 2" past the bottom of the unit, just worried it might act like a big trim tab, but i guess thats better than an anchor. I pulled the adjustment pin out to see what it would be like tucked in a little more(reverse lock doesn't work anyway). Took it for a run last night but lake was way too choppy, holeshot seemed better, but still not what it was. this little boat hard to control in chop, bow so light that the waves keep moving it around and can't steer. I'll try it again and see what it does as it was just me and i need to adults in it to compare what it does. The only thing i notice is that when your trimming up a little at a time it seems to start grabbing air(sounds like thats what prop is doing) when your trying to get up to speed, even though it is deep in the water.

 

[walleyehed]

Re: Proper engine height

You need an alum shim to go from the inside of the bracket(flush with outside edges, fwd and flush with boat bottom. It can be easily welded in.
I wouldn't lower the engine...I'd go for a higher tech prop like a stiletto triad or a MWC Rapture in SS. The little Rapture is a good prop, but the triad seems to hold higher.

 

[diaric]

Re: Proper engine height

i can't quite picture the shim your describing, are u talking about a splash guard like the others but its dropped down to be flush with the bottom of the hull. about a different prop. its a 66 merc 500, 11 spline hup. i don;t see anything listed for this, but i'm looking at retailers as i haven't come across the company site. the only props i've come across are a michigan wheel and propco, i have a new propco 11 pitch

 

[diaric]

Re: Proper engine height

walleyehed, i need a little more help on the shim your describing, do u mean flush with the boat bottom or just paralell with it? took it out yesterday with 2 adults, and splash guard, and hydrofoil. same as b4, hole shot gone, but hit the 30 mph it hit b4. i might take this propco off and try the 40 year old merc prop and see what it does

 

[walleyehed]

Re: Proper engine height

Not ignoring you, but I'm trying to get a pic of one with a plate and shim to show you...and yes, by all means, test any and all props you have.

 

[diaric]

Re: Proper engine height

thanks,, wasn't sure if u saw my questions. Here is the splashguard i quickly threw on. Its not paralell with the boat bottom, but that could easily be changed. when the wind dies down tonight, I'll try with the other prop, and take off hydrofoil to see if this splashguard makes a difference. And yes, i know i should probably cut the length down a bit, but this was just a starting point

 

[diaric]

Re: Proper engine height

so, i put the old prop i have back on and the hole shot improved, i don't think it as good as b4 but much improved. don't know if this was the stock merc prop as no numbers on it exept 11 for pitch. so this new propco one just doesn't do it for my boat, which is about the only prop i can find. look identical except exaust hub is half inch shorter than the old one. i can see that even with splashguard, tilt trim is dragging in water till it gets upto plane by the wake coming up off it. not sure if this old prop need rebuilding as the WOT speed varies and when running back to shore engine started screaming like hub was slipping or the prop started turning air. Don't know how to check it out, or what to do with this propco one now, its the same pitch, same top speed, but hole shot is poor and turn manouvering is not the same

 

[Crownie2]

Re: Proper engine height

The "splashguard" does look a little too long. The ones I have seen stick out about one inch past the plate and that last inch is angled up somewhat, I assume to reduce drag. That might help.

May I assume you added the tilt&trim mainly to get the trim feature?

Bob

 

[diaric]

Re: Proper engine height

yes, it was added to get the trim feature and the lakes around here are fairly shallow for quite a ways. i know splashguard is long, and i've got somw aluminum and stainless around here that i could make more permanent. just waiting for advice on how it should be made and mounted. tried googgling it but didn't come up with anything.still not sure if everything mounted the way it would work best as i get ventilation issues if i trim up slightly too much when the engine is working up to WOT. Looking for a tach that will work with this so i have a better idea where i'm at. when its at WOT, engine seems to be a little high rpm, if i back of throttle slightly it sounds better and speed doesn't change

 

[Crownie2]

Re: Proper engine height

From what you said above I would say that at some point you are probably going to need a better prop - and I certainly don't know what is out there for your motor.

Good Luck
Bob

 

[diaric]

Re: Proper engine height

I don't think the prop is the big issue here( I guess I'll have to call propco as that is the only prop I can find). Engine height and a proper splashguard is. With the motor trimmed parallell with the bottom of the boat, the av plate is about 2 inchs above with about 6 in set back. Even though I never trim up this high, so plate is actually lower in the water but at an in angle. I still haven't been able to try the old prop without the hydrofoil as its been pouring storming for past few days with frost warnings now. I do get ventilation issues when trying to get to WOT. so thats where I'm at

 

[Crownie2]

Re: Proper engine height

I just noticed that on the CMC site the Tilt&Trim is cut way back at an angle away from the transom. I wonder why your's is not like that? That would help a lot...

I'm looking at the model PT130...

Bob

 

[Texasmark]

Re: Proper engine height

I like their caution decal. Looks like that sucker could SHEAR off whatever gets in there while in motion.
------------------------------
With your remark about your current prop being ok, I went back and took another look at your setup.

You know what you need?

You need to get a friend in a boat with a camera and get as close to you as is safe, from 4 or so Pts abaft the beam (45 degrees out from the stern or thereabouts), and get some pics of where the water is when you are at WOT at your best trim angle.

Interested in the water stream off the transom (out from under the boat), back past the splash guard and onto the engine. Want to know where the antivent plate on he lower unit is located with respect to this. Want to know what is the engine's attitude (tilt) is with respect to this water flow.....for starters.

A pic (several if necessary) would be worth a thousand words here and we all would know what's going on so as to be able to fix your problem.

And last but least, a SS prop, the right SS prop will run circles around your alum prop....no brag, just fact. Only problem would be to get the right one. But everyone prop shopping has that problem.

Mark

 

[diaric]

Re: Proper engine height

picture idea is a good one,, i'll have to work on that. Don't have any friends with a boat that will keep up and its getting close to freezing right now so not to many boats out to ask. But I was out today fishing and damn was it cold at 30 mph.
I also noticed the cut away on tilt trim when i was browsing their site a few days ago. If you compare pictures of mine to the one on their site, the tiltiing motor mount appears shorter than mine.
Even with the splashguard the unit appears to drag on the sides if your only running upto about 2/3rds throttle. Noticed it today on way out in lake as chop was heavy and not running WOT. Steering is hard in this situation, spray comes straight up from sides of tilt trim and turning the wheel seems to tilt the boat more than turn it.
I would have no problem spending the extra for a SS prop. There arn't any as far as i know. 1966 merc, 11 spline hub, hard to find any prop. You would think that with interchangeable hubs they would make one for this.
I have ordered a tach, so hopefully it shows up before freeze up and i will have a better idea where I'm at for prop pitch,
i'll work on the pics

 

[diaric]

Re: Proper engine height

EMAIL TO CMC.
I have a pt-130 and am havinh a lot of trouble getting it set right for engine height. In comparing mine to the one on your site, I see that you have cut away the bottom portion of the transom mount and the tilting section appears to be shorter now. In trying to get this unit to perform properly i see that I have problems with the unit dragging in the water, by the wake spraying up off the sides of the unit untill i get up to WOT. What is
your
> > recomendations to solve this?
> > photo's of my unit

REPLY Yes, we shortened the motor rails of the PT-130 in 1996. The only way I see to correct the problem you are encountering is to cut away the excess aluminum rail under the motor lower mounting bolts. Best Regards,
NEXT EMAIL OK then, would you like to tell me how much you did the shortening by ? I don't want to ruin structural integrity. Is my problem the reason for this change?
NEXT REPLY Yes, weight and the problem you are encountering were the reasons for the change. You can cut up to the bottom of the adapter plate that your engine bolts through. Best Regards,


This will probably solve most of the drag issue at lower speeds, then I guess I can try to get engine height correct

 

[diaric]

Re: Proper engine height

I'm back, lots of pics and tilt trim is cut down.heres the boat sitting , showing how it sits at rest

here is the boat getting up to plane and speed

here we are up to plane and speed

any ideas, questions ?? there are more photos at http://s88.photobucket.com/albums/k176/diaric/

 

[Crownie2]

Re: Proper engine height

That last shot looks pretty good!

What is that turbulence to the starboard of the engine next to the transom in the next to last shot? What is causing it?

Bob