Outboard motors; Cruising, dingy, tips, maint, & reviews

[s/v Faith]

While doing the regular maintenance on my outboard I had an interesting 'discovery'.

  I have an 98 Yamaha 6hp 2 stroke (sold in 99).  It moves the boat well, and I have yet to figure out any valid reason to change it out... I had looked at the 4strokes but can not justify the cost for the slight benefit of potential fuel savings.

  Anyways, I opened the lower unit to change out the impeller (I have had the same one for 4 years) and found the woodruff key was half sheared off.  This is suprising because the key is much larger and thicker then I would expect would be required for this application.

  I had waited for months for the zink, so I was hesitant to go back to my local dealer for the part.

  I found; http://www.boats.net/ they have an excellent online ordering system that allows you to access the exploded parts diagrams online to see the exact part you want to order.

  I checked the prices on a couple of items and found they were lower then the dealer I have used locally (who is much More interested in doing business with the bigger motors then wasting their time with me).

[AdriftAtSea]

Thanks for the heads up on that... always good to find another good vendor.

[s/v Faith]

Update on these folks;

.......I found; http://www.boats.net/ they have an excellent online ordering system that allows you to access the exploded parts diagrams online to see the exact part you want to order.

  I checked the prices on a couple of items and found they were lower then the dealer I have used locally (who is much More interested in doing business with the bigger motors then wasting their time with me).

  I got my parts in, they were shipped quickly.  The throttle on this motor takes two cables, they are listed as a 'throttle cable assembly' in the IPB.  The quantity needed in this IPB is listed as '1'.  I ordered the one assembly, and received only one of the cables I needed.

  So, when the order came in I called outboards.net and had a person on the phone withinn 30 seconds of making the call.  She looked at the situation with me, and is fed-ex'ing me the second cable.

  Pretty happy with their service.   ;D

[AdriftAtSea]

I just picked up something that might be of interest to the majority of the people here, since most of the boats here are powered by outboards, rather than diesel inboards.

It is a very small Racor designed specifically for outboard motor type applications.  It will act as a fuel/water separator too.  Very cool.  It's about 4.25" high, to give you an idea of the size, and you can read about it at the bottom of this page here.  BTW, it is the middle one in the specs column, the other two are fuel filters but do not separate out water.

[CapnK]

I've been wanting to get a high thrust prop for a while, I finally did the research to find what I needed. Below are some links I turned up, to/about high thrust props for the Tohatsu/Merc/Nissan small 4 strokes. Maybe this'll save someone some time when they want to get one. :)

http://www.tohatsu.com/tech_info/prop.html  Tohatsu part #369W645120, specs: 7.9" diameter, 6" pitch.

http://www.nissanmarine.com/tech_talk/prop_chart.html Nissan uses the same numbers as Tohatsu.

http://www.usboatsupply.com/Mercury_Propellers.php

http://www.pws9.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=USBS&Product_Code=48-812951A+1

The last 2 links are for the aluminum Mercury Black Max High Thrust prop, 8 3/8" diameter, with a 6" pitch. The site in the last link has it for sale @ US$77.20.

Neat filter/separator, Dan - cool.

[AdriftAtSea]

I decided to get one, given the recent problems I've read about with ethanol mix gasoline.  Also, having additional filtration between possibly bad fuel and my engine is never a bad thing IMHO. 

Do you know if they make a high-thrust prop for the Honda 20 HP.  I've been looking for one, but haven't been able to find one yet.

[BobW]

Thanks Kurt links.

I've been planning to get a High Thrust prop for Prelude's old 6 HP Evinrude.  I haven't done much research but I'll start with the links you posted.  As an alternative, I have an 8 HP Mercury Mariner I could - and have - used on Prelude.

Dan, thanks for the link on the filter/separator.  I picked up a fuel filter but haven't added it to the system yet.   I'll look into the filter/separator and perhaps will install one of those instead.  No sense in pushing my luck since I wrote about my using old fuel.

[AdriftAtSea]

Anything that helps eliminate engine problems and reduces engine maintenance problems is a plus in my book.  Also, making the fuel delivery system on my boat more reliable is definitely a plus as well. 

While there is alot written about using filters and water separators for diesel inboard engines, there isn't really much said about them for auxiliarry outboard motors... 

Probably wouldn't hurt to add one to your dinghy's fuel system either.

[skylark]

When I researched removing the inboard and switching to an outboard on my 28' Tanzer, one of the goals was to get adequate performance from the smallest motor possible, this was for cost, weight and fuel efficiency reasons. 

A high thrust prop was one of the ways to get more thrust from less motor (in theory).  It was on my list of things I wanted when I ordered the motor.  I found out I could not buy a new motor with the thrust prop, but would have to order it separately and pay the additional amount.  The guy on the phone said, why don't you see if the regular prop works for you, you can always order it later.  So I did not order the thrust prop at the time. 

The standard prop seems to work fine and has gotten me out of harbors dead into the wind and 6' waves.  I'm not sure how a thrust prop would improve on this, maybe better efficiency, or better engine braking?

The critical issue with my outboard is not a lack of thrust, it is cavitation when coming down off of a wave, which limits how high I can set the throttle.  I have to run it at low rpms in wavy conditions so it doesn't over-rev coming off the wave peak.   I don't think a high thrust prop would help with this. 

If props are listed as 6", 7" 8" and 9", which is the high thrust prop?  I think it would be the 6", is this correct?

The idea with the high thrust prop is that you can get the outboard up to proper rpms and the prop will be matched to 4 to 6mph travel through the water, instead of 15mph that you might see with a runabout.

I like to run my 4 cycle at low rpms so I am not sure that a thrust prop is the best choice.  The standard prop moves the boat well and doesn't use much fuel. It works in flat water as well as wavy conditions.

[CharlieJ]

we push Tehani's loaded 7000+ pounds with an 8 hp 4 stroke Yamaha, with a standard prop. 

We've got some 2700 miles behind us in the ICW using that motor. We usually run at hull speed or just under that, with the engine set at a high idle. Less rpm than at the "start" position.  Aginst tide, against current in locks, and against winds where we could not sail. That prop has done extremely well for us.

Running at a setting higher than the "start" position just squats the stern- she ain't running any faster.

We get about 7 1/2 to 8 1/2 hours of run time from a 3 gallon tank of gas, or average about 45 miles per 3 gallons.

Can't ask for much better than that.

The ONE thing a power prop MIGHT give us would be a better reverse. I have to admit with the stock prop, reverse isn't something spectacular. But then Tehani has a long full keel, so I don't think we'd do a lot better reversing with ANY power plant, including an inboard. She's just slow to back up and very slow to turn. Once you learn her ways, it can be done, but slowly.

I'd be afraid we'd lose the gas mileage if we went to a power prop, for little gain in performance.

[skylark]

I run a 6hp 4-cycle Tohatsu. I have never felt that I was underpowered.  I don't have to deal with tides and not much current, just river currents.  I also sail whenever I can, I will beat to wind rather than start up the motor.  Its open water and usually windy here.

Another theory:  thrust props are important for two stroke engines, where they need to run at a higher rpm to run well.  Thrust props are less important for four cycle engines which can run well at lower rpms.

[Pixie Dust]

I bought a Tohatsu 3.5 -4 stroke prior to leaving Panama City.  The distributer told me to ALWAYS lay it handle side down or oil will go in the carb.  The book said differently, so I followed the book and placed it on the little legs.  When I took it in for servicing, the very helpful guys put it in my trunk for me.  When I opened it, it was handle side down.  THEN... when getting it off the back of my boat and onto the dinghy and back onto the boat, she got rolled a little in mid air and in the dinghy.  That did it, my always start on second pull Tink pusher was not willing to start or even sputter.  2 nice guys stuck in the same anchorage as me due to weather spent about 2 hours with me troubleshooting it. They were headed north to KY. Tohatsu was great!!  Gave me a dealer here in St. Pete they like, told them to put it under warranty for me and bingo!!  I had my outboard back and running by Monday evening.  Thank goodness.  I am ready to move further south!!  4-strokes are very finicky about which side you place them on.. and prefer to be straight up.   If oil gets into the gas and or carb, they will not start for nothing.  Lesson learned with 4 stroke, if this happens again, take out spark plug, open screw on bottom of carb. pull out choke and pull start over and over until all runs clear.   Thank you Tohatsu for great service!

[AdriftAtSea]

Thanks connie... good to know.. I'm planning on getting a 2 or 3.5 HP four-stroke for the dinghy at some point this year.

[Pixie Dust]

I have a 8'9" air floor Mercury Dink and it pushes it pretty well.  Difficult to get on a plane, so added an extension out of PVC to the arm  and it does much better.  If I get in the bow for even a minute and get it on the plane, she will scoot.  I had to stick with 3.5 due to wt- it is 35#, but if you can move up to 4-5hp, it should plane much better.
I now have a motor sling and lift it on and off Pixie with a hoist.   SOOOOO much easier and the engine stays level.  I highly recommend the motor sling.  Makes controlling the relocation of the outboard so much easier. 

[BobW]

I've heard it is unwise to lay a 4-cycle outboard on its side, particularly the "wrong" side.  This causes oil to flow into the wrong places and damages the motor.  In a chat discussion the other night, there was some debate whether this is a real problem or not.

Since I don't have a 4-cycle motor, I need not worry about that particular issue.  But what I didn't ask is whether that same caution applies to a 2-cycle outboard.

The reason I ask is I am rebuilding my outboard well and trying to figure out how to raise the motor out of the water while sailing.  One option - admittedly not the best one - is to manually lift the motor out of the well and stow it on its side in the lazarette.  I would test this method while working out the details ofraising the motor mechanically.

Can I do this without damaging the motor?

Thanks.

[AdriftAtSea]

BobW-

Doesn't apply to two-stroke engines AFAIK, since two-stroke engines don't have and oil sump, like a four-stroke engine does.  The oil used for lubricating a two-stroke is in the fuel, while the oil used to lubricate a four-stroke motor comes up from the sump, and if the outboard is laid down on the wrong side, the oil can pour out and get into parts of the engine where it will cause problems, like the carburetor.

[CharlieJ]

Certainly Bob. The problem with the 4 stroke motors is the oil sump. The 2 stroke has no sump, no oil inside the case, except when running, since it's mixed with the gas. So unless it runs out of the carb bowl, there's nothing to leak over.

And it WILL screw up a 4 stroke.  We both know someone who tilted a small 4 stroke to far over while it was on a transom and almost ruined the motor trying to start it with the oil in the cylinders. Remember T.P.?

[BobW]

Thanks.

That's good to know (should have been able to figure that out on my own!).

[Pixie Dust]

Bob- What you heard about 4 strokes is absolutely true.  I was living proof of that little error a week ago.  Now that I am fully educated and have a motor harness with a hoist on board, this hopefully will not be a problem in the future.   Finicky little things when it comes to that.  Can you imagine sleeping on one side only for ever???  ???

[BobW]

Is there a way to measure/determine the pitch of a propeller?

I pulled the prop off my 6 HP Evinrude to see what the diameter/pitch are, but the numbers are nearly gone.  I can read 8.5 x ... but the pitch is illegible.  (What I need is some of the acid they use on "CSI" to recover serial numbers ground off handguns.  :) ) 

I may have to take the prop to the shop and let them match it.

I've been trying to track down a high-thrust prop (9 1/4 x 6 1/2).  On Kurt's suggestion, I contacted onlineoutboards, but they don't carry props for Evinrudes.  I went to the local shop, and they discovered the high-thrust prop for my motor is no longer available.  They referred me to Seaway Marine (in Seattle) who specialize in old out of production parts.  They don't have any in on hand but referred me to 4 other possible sources.  Email inquiries to those 4 have gone unanswered.

But if the prop I have is 8.5 x something, I may not get $80+ worth of improved performance.  However, I probably need to replace this prop soon as it is showing some pitting.

So, is there a way to determine the pitch?

Thanks.