2 mishaps I had that caused damage My Fault??

[BOAT]

Wow, I did not know the exhaust come out of the prop. That's cool.

Matt - I did not know about that ramp - and it's in the big bay - right?

[Russ]

If the Power Thruster did not improve slow speed maneuvering, reverse prop thrust, reduced prop walking and faster out of the hole I would not have posted the link here. It would have been boxed up and sent back for a full refund. 3 years of testing on my and all of the above apply.

I don't think there is any measurable gains in fuel economy but I can troll all day on two gallons of gas.

There seems to be a bit of controversy over the effectiveness of these devices. As you stated, if they didn't work, people would remove them and send them back. However, I have to wonder why manufacturers don't incorporate similar designs out of the box. What I have read is some claim they reduce top end performance. Benefits seem to be protection of the propeller from hitting objects. I don't have any experience or an opinion one way or the other.

The E-tec (and all other modern engines) exhausts combustion gas thru the prop hub--at no time does it inhale the exhaust. Cooling water is pumped into the power head from vents in the lower unit and peed out the back of the power head. Reverse prop efficiency is diminished by the exhaust gas but the PT's nozzle effect magnifies the thrust-especially with a 14" prop.
Bob

In the context of this thread, OP had loss of thrust when throwing the outboard quickly into reverse ("I quickly pushed the throttle back full reverse and the boat KEPT GOING FORWARD!! The motor sounded funny"). Since the engine exhaust is through the propeller hub, it's feasible that when the prop reversed it sucked exhaust back forward, thereby reducing the "bite" the prop had. Instead of drawing water as thrust, it was churning exhaust gas mixed with water. Just a theory, but I'm trying to find an explanation of his inability to stop the boat quickly.
With that said, I've reversed quickly and had a slight loss of reverse thrust, but not total loss from this situation. Maybe full reverse caused excessive exhaust gases, I've never used full reverse throttle.




--Russ

[mastreb]

Wow, I did not know the exhaust come out of the prop. That's cool.

Matt - I did not know about that ramp - and it's in the big bay - right?

Yep. Take I5 south to "Bay Marina" Exit.

[mastreb]

Listening to the symptoms, I think you may not have gotten the boat in gear. If you went straight through from FWD to reverse without stopping in neutral, there's some chance that the transmission missed the reverse gear and wound up stuck in neutral or not fully engaged. This would have resulted in high RPM, perhaps a grinding or rattling noise, and the boat continuing forward under momentum.

[BOAT]

You bring up a good point Russ, because I noticed the web site for the "thruster" said is was for 'SAILBOATS'.

Sailboats are SLOW, and they need more 'thrust' because they can't plane. The MAC M and X will pop right out of the water and plane faster than any regular sailboat with an outboard will ever go. I think you may have hit the issue dead on - I think that big piece of metal is going to be a problem at 22 MPH as it grabs water and tries to force the motor low end unit up and down.

I think Russ has a point - I don't think that unit (thruster) would be a good idea for WOT on out type of boats.

Matt,

Just looked at that Marina - GREAT! and the bridge (Coronado) is no barrier to us like the bridges in Newport, and Los Alamitos and Queens way - right?

[EZ]

Could the prop be cavitating? I think I have had this happen to me when going from reverse to forward. RPMs went high, no forward motion. I looked behind me and saw a whirlpool next to the engine.

Put the engine in neutral. Whirlpool went away. Shifted to forward and all was good again.

[bscott]

Now that the subject of "high speed" vs the PT is in discussion I can report that the PT at 16 knts--my top speed-- held a straight course with less bow rise than before the install. I tested the top speed with and without the PT on the same hour on flat water, no wind. Same top speed. The PT is designed for heavy displacement hulls which is what the and are at displacement speeds.

As far "Why not the OEMs?"--their approach to semi-displacement hulls and pontoon boats is selling us lower units with 14" props as found on 50/65 hp E-tecs and Big Feets. They let the aftermarket guys develope "special use solutions" since unit demand is so low

I have never had the need to exceed 2,500 rpm with the PT to fully stop my within 6' of the dock so maybe a high rpm reverse does severely ventilate/cavatate the prop with exhaust gas. The E-tec's ECM actually electronically reverses the engine power head rather than using a forward/reverse lower unit gear box. You might check out the throttle position sensor--TPS-- which could be out of adjustment not allowing the engine to immediately reverse itself.

For anyone that relies on the lower unit to steer the boat while under sail, think Power Thruster

Bob

[Catigale]

The E-tec's ECM actually electronically reverses the engine power head rather than using a forward/reverse lower unit gear box.

IS that right? First time I had heard of this. Can you make a FIJ 2 stroke run backwards?

[BOAT]

All this motor stuff is confusing - Sails are better. I guess I better learn about motors now that I have a MAC.

I removed the port rudder and corrected the slight deformities in the bracket yesterday. After putting the rudder back on I went ahead and added the mod invented by "My Blue Heaven" (A blue hull MAC M I saw here on the site), Forgive me but I don't know the skippers name but the boat's named My Blue Heaven. His mod adds turn blocks to the rudder ropes so it's real easy to pull them out of the water. I now have the turning blocks too.

The daggerboard damage was filled with the Marine Tex you guys suggested and just today I sanded down the Marine Tex and put a strip of fiberglass cloth on that entire top edge and the resin job is in the sideyard curing as I writhe this. The daggerboard should be stronger against damage now, but not as strong as the daggerboard that Jack Sparrow invented with lead ballast and a wing on the bottom. I like his daggerboard but I'm not that experienced with shaping fiberglass so I passed on it.

Rudders look great, the board should be ship shape by this weekend after a good sanding, so the only thing left to deal with is the motor reverse and I'm really hoping that's just me being inexperienced with such a large outboard, (back in the day we only used 10 and 15 HP motors on out sailboats because anything bigger was a waste).

I'll send pictures when done. YOU GUYS helped a lot with good advice and that made my repairs go very fast and very easy. Thanks

[Spector]

The E-tec's ECM actually electronically reverses the engine power head rather than using a forward/reverse lower unit gear box.

IS that right? First time I had heard of this. Can you make a FIJ 2 stroke run backwards?

This is the approach on 2 stroke snowmobiles but I just looked thru an Etec manual online and it made no reference to running in reverse

[bscott]

The E-tec's ECM actually electronically reverses the engine power head rather than using a forward/reverse lower unit gear box.

IS that right? First time I had heard of this. Can you make a FIJ 2 stroke run backwards?

This is the approach on 2 stroke snowmobiles but I just looked thru an Etec manual online and it made no reference to running in reverse

I have an 04 and 12 BRP Skidoo 800cc snowmobile both of which have electronic reverse and I was told by the dealer that the 02 Skidoo's Rotax carbed 800r and the new E-tec 600/800 cc had the same reverse system as the the Evenrude E-tec.

I just pulled up the parts diagram and there is a forward/reverse gear--so I have to eat crow on the World Wide Web about the Reverse function of the Evenrude E-tec.

Bob

[BOAT]

Shoot, I get crow so much on this site I eat it for breakfast now. I'm starting to get used to the taste.

[Catigale]

I make a mean crow filled humble pie....gets raven reviews...

[mastreb]

BOAT, I do think you just missed the gear. The throttle requires a stop in Neutral between FWD and REV. In a panic, you likely forced the throttle through it without stopping, which caused the gears to miss synchromesh and grind. That would account for the lack of power and the funny noise, all solvable by going into neutral and then back out.

[BOAT]

Anything is possible - i was just to busy trying to stop to look under the seat at the motor