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Thread: Nissan 6 HP 4 cycles

  1. #31
    Join Date
    Sep 2008
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    Harpswell, Me. (where we sail) and Austin Tx.
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    16
    Thanks for the input. Looks like a 6hp. Tohatsu is in my future. I'll try just keeping it stowed over the summer until I need it. I would love to retro fit an inboard, but the cost would be more than I paid for the boat.
    Thanks again,
    Lou

  2. #32
    Join Date
    Mar 2006
    Location
    San Francisco - or Abroad
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    430

    Comments on outboard performance - experience so far...

    Here is a bit from my experience on the issue of outboard performance addressing some of the most common issues brought-up on the board:

    The 'Mephisto Cat' is a 'Well in the lazarette' / outboard model' from the factory. I am happy to not have to deal with an oily bilge! Although I could learn a thing or two about diesels... And I salivate a the big & handy storage space that is available in the lazarette to those of you with inboards... Hmmm...

    I can only dream of the day when a nicely suited electric motor is available!

    In any case; So far I've used a 2003 NISSAN 6HP, 4-stroke outboard engine with the long shaft (20”) on the Mephisto Cat. This NISSAN model, as well as some other brands (Mercury?), is apparently made by TOHATSU so they share the same mechanicals - only the marketing bits are different...

    I’ve used this motor for a handful of seasons in San Francisco Bay, as well as at Marina del Rey (Santa Monica), and on coastal voyages from Ensenada, MX, to San Francisco as described in previous posts on the Mephisto Cat gallery thread: http://www.pearsonariel.org/discussi...ead.php?t=1552

    The typical issues faced with outboards on Ariels & Commanders seem to be the following:

    1.- Will the motor fit in the outboard well?
    The 6 HP Nissan fits quite nicely in the well being able to rotate pretty much throughout its full range. The lazarette cover closes, clearing the top of the motor by two to three inches. (I am unsure if the internal tank version of this motor would fit as the internal fuel tank cap is located at the top of the motor cover, and sticks out at least a couple of inches...)

    The bottom unit is thin & slender (unlike some other brand's models) allowing for an easy fit in the well (there are maybe 3" inches to spare around the widest part of the lower unit as you lower it thought the well...) The slenderness of the bottom unit also helps in reducing hydrodynamic resistance while sailing with the motor in the motor well – which I often do….

    This motor only weighs 55lbs (Per Nissan) which makes it easier to handle. I think that this is the heaviest you can go while still being able to (relatively) easily handle an oddly shaped mass as an outboard motor - especially at the point where you are lowering it into / pulling out of the lazarette.

    2.- How much power do you need to power an Ariel / Commander (HP)?
    I find that this motor moves the boat quite well. It will cruise at about 4 to 4.5 knots at ¾ throttle, and will reach hull-speed (~6kt) at a bit less than full throttle.

    While sailing in SF bay in the past, where the winds and currents are not to be ignored, I have found the need to use the full power of this motor while fighting a strong current, or while motoring into a channel with a strong wind on the nose.

    While using the motor during coastal cruising, I found that when faced with strong winds on the nose - and the resulting long-reach wind swell - the going gets slow... Mostly because out in the open, the wind swells easily kill your forward momentum.

    In these cases a bit more horsepower might help, but these are unusual circumstances for these boats. AND I would argue that if you find yourself in this situation at that point you’d be MUCH better off sailing-off with a reefed main and a storm headsail as this will improve your ride and likely progress as well, so the benefit of a bigger outboard in these cases may never be enjoyed… while you’d ALWAYS be burdened by the big outboard’s weight. **

    However, in my time spent in coastal marinas, such as Marina del Rey / Santa Monica Bay where currents are negligible, I found myself wishing for a little (maybe 2-3 HP at most) two stroke motor that I could pull out in a jiffy… This would be more than enough to get in and out of the marina when the winds were blowing. If I were still in this environment, I’d definitely go with the tiny motor. If you are in a lake environment doing mostly daysailing, I'd really consider this route...


    ** As I've learned more about this issue, I found that the ideal solution in this case (from a hydrodynamic standpoint) is not really more horsepower, but rather a larger prop diameter at a lower pitch to increase efficiency of the available force... Providing what is known as increased 'bollard pull' -the equivalent of more torque in a car engine- with the same horsepower...
    Unfortunately, these motors will not physically acommodate a prop much bigger than what comes from the factory...


    3.- How fast will the boat go?
    6HP will get you to hull speed in most conditions. There is no need for more horsepower. - 20HP will maybe give you hull speed PLUS maybe 1 or 2 knots more, PLUS a big bow wave in front of your boat… and this while using MUCH MORE Fuel. In short, there is no need… (unless, as I described above, you will be ONLY sailing against very strong winds in sheltered waters -with no wind swell. These conditions would allow you to enjoy the extra horsepower to fight the wind, but these conditions are unlikely…)

    4.- Shaft length
    My motor has the 20” long shaft. (Note: For 2009, Nissan is offering a 25” extra-long shaft.)

    I found that the 20” long shaft works really well on these boats. The steepest swells faced were while motor sailing around Point Conception where we saw 8-10 ft ocean swells that were far apart enough to not present a problem (11-14 seconds). Big swells are not a problem for the motor, but when these swells are reflected by the concave coast between Point Conception and Point Arguello, and become 4-5 ft swells coming in opposing directions, plus toss in a 1-2 ft wind swell… All of these combining at random can present a tall chop which can be a challenge mostly for your comfort.

    Even in these conditions the prop managed to stay in the water but did suck in some surface air for an instant a couple of times as the conditions above combined to produce a steep/deep chop. Note that when the cavitation happened, it was quire unexpected based on the behavior of the boat at the time, and never due to a severe pitch or roll - the prop seems to stay in the water while pitching /rolling. What seemed to do it was simply a very tall / steep chop, in my case, resulting from a combined wave/swell.

    The cavitation was only for an instant causing the revs to increase, but only for an instant. I do not think that the motor had time to reach max revs. I do not think that cavitation is an issue for the 20" shaft lenght based on the amount of time that the motor had to work in these conditions...

    In short; If I were in the market for a motor, I'd stick with the 20" version...

    The 25” shaft would provide a bit more of a margin against the above situation, but most of us would not be in this stuff as a matter of routine… (hopefully!!). The down side of this extra length would be a bit of additional drag while sailing, a small bit of added weight, and the 5 extra inches increasing the required storage space.

    Thoughts?
    Last edited by Rico; 04-20-2009 at 09:03 PM.

  3. #33
    Join Date
    Jul 2007
    Location
    South Portland, Maine
    Posts
    16
    I'm interested if anybody bought the extra long shaft and how their experience was. Orca's 1990 Nissan 8 seems like it has coronary salt disease and is shutting down when you run it hard so I'm thinking of the Tohatsu 6 hp. Whatever my shaft length is now (NS8B1) it definitely has scared me in some serious chop by racing out of the water. I'd be interested in first hand experiences for the 25" and how it fits in the lazarette, if at all. I've kept mine in the water over the years as I end up using it quite a bit in Casco Bay and it seemed like a pain to lift it in and out. Also, I'm at a mooring so fresh water cleaning when you pull it out is not possible and I think that salt build up will happen quicker if your always pulling it out. I arrested the pitting of the case when the tiny donut zinc dies by drilling two holes in the captivation plate and attaching a big zinc I sawn in half. It seems to last more than a season. I'll have to get out to the mooring and measure the shaft if somebody doesn't know which shaft I have based on the model.

    Thanks, Ed

  4. #34
    Join Date
    Sep 2001
    Location
    Santa Cruz, California
    Posts
    447

    I have one of those.

    I purchased the Nissan 6 horse four stroke motor for my Ariel, Augustine, a few years back. My boat operates in saltwater, so I remove the motor after each sail. I use the Garhauer Lifting Davit, which was installed as per the Ariel Manual. The davit is stored in a bow (as in a hunting bow) bag, which I keep in the V berth when it is not in use. The six-to-one ratio on this davit means that you are only lifting about 10 lbs when you raise and lower the 60 lb Nissan 6 hp motor. It's a one hand lifting job.

    I also flush the motor after each use, unless I am on a multi-day voyage. To facilitate the flushing process, I installed a Yahama flushing apparatus that allows a quick connect/disconnect to a garden hose. Flushing is easy that way. The motor stows nicely in the lazarette locker, although you will need a block of some kind to keep the head of the motor higher than the prop when stowed.

    By the way, don't go to sea with the motor stowed in the lazarette locker. I know someone who did this. Not a good idea to have the motor head down in a locker full of salt water when you are on a starboard tack. I just leave the motor in the water while I sail. It helps to have some neoprene to protect the leading edge of well where the motor attaches, and to insure that the motor does not rock back and forth and come loose from the leading edge of the well when under sail in rough conditions at sea. Some brave souls remove their motors and stow them in the cabin. I have pulled a motor at sea with my lifting davit to replace a prop, but the installed davit is in the path of the boom, so this should be attempted only at rest or at peril.

    The long shaft motor operates well in all conditions, but I rarely run the thing at sea. I primarily use it to get under the bridge and out of the harbor. I only had the motor aerate on me once when I struck the bar while in a trough when I was surfing into the harbor here one late autumn day a few years back. The boat stopped cold when it hit the bar, and the stern rose up through the breaking wave so that the prop was for a few seconds out of the water. Then the wave lifted Augustine off the bar. That was at night, so it was pretty exciting for a few seconds.
    Last edited by Scott Galloway; 07-04-2009 at 09:10 PM. Reason: found error
    Scott

  5. #35
    Join Date
    Jul 2007
    Location
    South Portland, Maine
    Posts
    16
    Quote Originally Posted by Scott Galloway View Post
    The motor stows nicely in the lazarette locker, although you will need a block of some kind to keep the head of the motor higher than the prop when stowed.


    The long shaft motor operates well in all conditions, but I rarely run the thing at sea.
    Thanks Scott, I assume this is the 20" long shaft?

    I've not been in the habit of removing my motor as being on a mooring I have no access to freshwater for flushing.

    When I first started sailing my boat some 12 years ago, I recall the lazerette often filling with water. It hasn't happened much since then. I can't think of what might have changed. I have one of the outboard motor plugs that came with the Ariel but I've not used it much.

    Thanks, Ed

  6. #36
    Join Date
    Jul 2007
    Location
    South Portland, Maine
    Posts
    16
    I didn't get any response so I'll assume that means nobody who has followed the thread bought the 25" shaft version. I ordered one so I'll let folks how it fit etc. Thanks, Ed

  7. #37
    Join Date
    Apr 2008
    Location
    Forsyth GA
    Posts
    396

    outboard motor plugs

    Does any one have a spare outboard plug?
    Mike Godwin posted fabricating these one time , Did that ever materialize?
    Thanks

  8. #38
    Join Date
    Apr 2004
    Location
    Pensacola, FL
    Posts
    722
    Quote Originally Posted by Orca View Post
    I didn't get any response so I'll assume that means nobody who has followed the thread bought the 25" shaft version. I ordered one so I'll let folks how it fit etc. Thanks, Ed
    No one (including me) with the 20" shaft has reported cavitation that I recall. The 20" shaft fits in the Lazy-rat.... not sure if the 25" would. Any longer shaft then the 20 just gives more drag when sailing, so I am not sure why anyone would want it.

    My experience with my prior (20") yamaha tells me that 20" is all you are ever going to need.

    I have not run a 25" shaft so I have no first hand experience but can not see where you would gain anything but drag. If you do not take advantage of the motors ability to pivot when backing and rely on prop wash over the rudder you may see some improvement in backing.

    I hope it works out well for you.


    s/v 'Faith'

    1964 Ariel #226
    Link to our travels on Sailfar.net

  9. #39
    Join Date
    Jul 2007
    Location
    South Portland, Maine
    Posts
    16
    Well, the weather finally settled a bit here so I took the Nissan 6 HP extra long shaft (25 inch) down to the mooring today and installed it. I checked and it fits sideways in the lazarette just fine. I found that the top of the motor barely cleared the top of the lazarette which makes me wonder if the mounting board is higher than other boats as somebody previously reported 2 or three inches of clearance. I think I have less than 1/2 inch clearance.. I intend to visit Orca in the AM and motor around a bit. I think its a bit noisier at low speeds than the 8 HP I took out and it isn't as smooth because it is a single cylinder and the old engine was two cylinder. I'll report back on how it handles with the prop around 10 inches more underwater after I use it a bit.

    Very Best, Ed

  10. #40
    Join Date
    Jul 2007
    Location
    South Portland, Maine
    Posts
    16
    Quote Originally Posted by Orca View Post
    Well, the weather finally settled a bit here so I took the Nissan 6 HP extra long shaft (25 inch) down to the mooring today and installed it. I checked and it fits sideways in the lazarette just fine. I found that the top of the motor barely cleared the top of the lazarette which makes me wonder if the mounting board is higher than other boats as somebody previously reported 2 or three inches of clearance. I think I have less than 1/2 inch clearance.. I intend to visit Orca in the AM and motor around a bit. I think its a bit noisier at low speeds than the 8 HP I took out and it isn't as smooth because it is a single cylinder and the old engine was two cylinder. I'll report back on how it handles with the prop around 10 inches more underwater after I use it a bit.

    Very Best, Ed
    Hi: After using it a bit I can tell you the following. The 6 HP 4 cycle is quieter than my 8 hp 2 stroke Nissan but not quite as fast into the wind. It does seem to do something close to 6 knots when its calm (I'll have to wait a bit to try duing a slack tide as I rely on the GPS which showed a range of 4.8 to 6.5 knots over the ground). The clearance is less than 1/2 an inch on my boat and seems to touch the top of the lazarett when under load. The lazy rat buggered up the top of the motor a little so I now jimmy it open a little when running. My old motor was a 15 inch shaft. It had some issues in rough seas and was pretty much useless if a bigger person went up on the bow. For my money I think the 25" shaft is good insurance for some of the high chop that develops around here in the river mouths like the Kennebec where closely spaced, steep 5' or larger standing waves are a regular occurance . . . I suspect that 5" additional shaft would not be enough. The extra depth makes it a lot easier to back the boat down. The fuel economy is very good. After a few hours (mostly at 3/4 throttle or less) the little tank is still showing mostly full. I'm glad to see that the fuel connection on the motor has been reconfigured. I had to buy several of the old connections on the Nissan before I found one that worked.

    Thanks, Ed

  11. #41
    Join Date
    Sep 2001
    Location
    Santa Cruz, California
    Posts
    447

    motor clearance

    My Nissan 6 hp long shaft motor also has a clearance of about 1/23 inch. I use a Garhauer lifting davit to lift it into place. The Davis OB lifting strap that I use to lift the motor has a somewhat round cover that joins the two sections of the webbed straps. With that approximately 1 inch round addition added to the motor height, the lazarette barely closes and latches with some pressure, but then again, I don't normally latch the locker when under sail. Incidentally it was a great 10 to 12 knot sail out over the Submarine Canyon on Monterey Bay yesterday.
    Scott

  12. #42
    Join Date
    Apr 2002
    Location
    Houston, Texas
    Posts
    290

    Nissan, Tohatsu, Merc 6 hp Starting / Exciter Coil

    To continue on with comments on the 6 hp four strokes all made by Tohatsu, I've had mine running since 2004 and have some comments on maintenance. Everyone knows by now that its a good idea to drain or run excess Ethanol 10% gas out of the carb if you aren't going to use the outboard every two weeks or so. Gas stabil is almost a must because the ethanol absorbs water. Over the years, I've found that the common reason my motor wouldn't start or idle well is bacause of clogged jets from fuel. In Houston, with 95 degree temps every day in the summer, it doesn't take long to evaporate all the fuel and leave the gunk behind in the carb. I've cured any problems by disassembling the carb and soaking in carb cleaner. I've found that the spray cans don't do a complete job. However, I recently found that hard starting and engine dying was because of an ignition problem---- not dirty carb issues. I used a spark tester and found I wasn't getting a spark on each pull of the starter roper. I got out the Tohatsu factory manual (the real deal which I purchased from Defender) and tested the resistance of the ignition coil, the exciter coil (which sits under the flywheel) and the pulser coil-- which is at the edge of the flywheel under the starter rope hole. Most of the coil resistance tests allow a plus or minus 20% reading from the factory spec, and still be good. But my exciter coil was off spec. The exciter coil generates the low voltage current, sends it to the CD unit (that little black box with all the wires leading to it). The CD unit stores this energy until its told by the pulser coil that its time to fire the plug. The CD then sends voltage to the ignition coil (roundish black epoxy coated coil connected to the spark plug wire) which then steps up the voltage to fire the plug. The factory resistance of the exciter is supposed to be 119 ohm plus or minus 20%. Mine was reading 78. So there was a developing short somewhere in that coil, and it wasn't generating enough voltage at low rpm or, most importantly, when I pulled on the starter rope! I put in a new coil (they are about $30) an now the motor starts on first or second pull-- like when it was new. The hardest part of this job was getting the flywheel off. You can read online on how to do this properly. You can mess up the flywheel and do some real damage if you don't use the right tools. With the right tools, its easy.

    As you engine ages, and it starts getting harder to start and idles less reliably, check you coils. I didn't think modern coils failed very frequently, but my experience shows that they can and do.
    Last edited by Hull376; 11-04-2010 at 04:38 PM.
    Kent

  13. #43
    Join Date
    Apr 2004
    Location
    Pensacola, FL
    Posts
    722
    Has anyone successfully figured out a way to add a more significant zinc to these motors?

    The fingernail sized one they come with seems to last about 15 minutes or so...


    s/v 'Faith'

    1964 Ariel #226
    Link to our travels on Sailfar.net

  14. #44
    Join Date
    Sep 2001
    Location
    Orinda, California
    Posts
    2,249
    The zincs have lasted several years on my 5hp, but then I don't leave the engine in the well except when motoring . . .

  15. #45
    Join Date
    Apr 2002
    Location
    Houston, Texas
    Posts
    290
    I ordered a Tohatsu 6 pitch 8" diameter High Thrust prop that Tohatsu makes for the 4/5/6 hp four cycles. I was using a 7" pitch which is less pitch than the standard prop that ships with these outboards. The high thrust propeller is the same one that they put on the so called saildrive version of these small four strokes. The results with the new elephant ear low pitch prop are very good and I'm happy I spent the $69 for it.

    1. Low end is much better at driving the boat
    2. There is far less hesitation when throttling up when the outboard goes between the low speed and high speed jets. I think this is because there is less resistance with the High Thrust prop which allows faster increase in RPMs than the 7 or 8 inch pitch.
    3. The outboard is achieving higher RPMs at all throttle settings, especially at the top end. With the old props, it always sounded as if my 6hp was "lugging" and not getting up to 5,000+ RPMs. Now the lugging sound is gone.
    4. The wide open throttle has now gone from 6.0-6.1 mph to 6.3 mph. So no loss of speed, slight improvement, but without the lug on the engine and without the hesitation and potential stalling that happens with the old props.
    Last edited by Hull376; 11-04-2010 at 04:54 PM.
    Kent

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