Yanmar repower

[jhenson]

I'm getting a sense that if one were to repower a Triton with a Yanmar, that the 2GM is probably ideal. I am wondering if a 1GM would be way underpowered for this application?

Joe

[Tim]

One issue with the 1GM10 is that is is available with only raw water cooling. At only 9 horsepower, it is sufficient to push the boat in most conditions, but there's no doubt that some additional power is worthwhile.

I think this engine would be a little small to be considered ideal in a Triton. It would also limit any thoughts about upgrading alternators or adding additional equipment. The single cylinder would be less smooth as well. To me, choosing this engine for a new repower would end up being penny wise and pound foolish, but it all depends on how the boat is to be used.

Yanmar has changed its product line slightly for the larger engines. There are now two possible engine choices suitable for a Triton:

The 2Ym15, at 14 horsepower;
and the 3Ym20, at 21 horsepower.

I think either of these new engines would be fine. The 18HP of the "old" 2GM20F, like I have, is plenty for the boat, even with a large alternator (80 amp).

Yanmar has a pretty cool new website with a 3D presentation of the new engine; you can rotate it from all sides. Detailed specs are also available there.

http://www.yanmarmarine.com/products/product_gmym.php

I can also speak highly of the Yanmar engine. I love my Yanmar. Money very well spent. I always say, if you have to have an engine at all, it must be reliable and appropriate for the boat. Otherwise, why bother? I learned my lesson the hard way with my "used" diesel that I originally tried. Never again.

[jhenson]

Tim,

Thanks as always. This boat will spend most of it's near term life in the confines of the somewhat protected waters of the Chesapeake. I am some years away from cruising the Atlantic coast and am not sure that I'll do so in a Triton (although I don't omit the possibility). That said, I guess I am trying to moderate the spending on this boat to the mission at hand. I certainly don't want to spend hundreds of man hours on something that will be junk either.

I'll show a little ignorance here and ask if upgrading to a larger alternator on a 1GM would be limited by a function of horsepower? If so, is there a way to know the price paid in HP to say double the standard 35amp alternator output?

Thanks again for your tireless devotion to this forum. I have enjoyed your responses to all my posts.

Joe

[dasein668]

Horsepower info from Nigel Calder's book....

An alternator's output is about 14 volts. At 100 amps an alternator is therefore producing: 14 volts x 100 amps = 1400 watts. There are 746 watts in one horsepoer therefore in theory this alternator will require 1.88 horsepower to drive it.

However alternators are only 50-60 percent efficient in energy conversion, so this figure needs to be doubled to 3.76 horsepower, and then a further factor added for other energy losses such as drive belt and pulley friction! This results in a power requirement of up to 4 to 5 horsepower at 100 amps. Obviously, at reduced loads, the alternator will need less power. (Note that large-frame alternators and large pulleys cause less power loss than small-frame alternators and small pulleys.)

A side loading of this magnitude on an engine's crankshaft pulley may damage the crankshaft oil seal or bearing. Before installing a high-output alternator, check with the engine manufacturer to make sure the motor can handle the load. . . .

Another problem that may occur with small engines and large alternators is that the horsepower absorbed by the alternator at times causes unacceptable propulsive power losses. This situation can be alleviated by fitting a sophisticated voltage regulator witha current-limiting capability that is set to keep the alternator's output below a certain level. [note from Nathan: that sort of defeats some of the purpose of a high-output alternator....]

If you don't have a copy, I highly recommend picking up a copy of Nigel Calder's Boatowner's Mechanical and Electrical Manual (click here for Amazon...) It's a great reference.

[Tim]

Even with my 2GM20F, I find the 80-amp alternator to be quite a draw. I originally installed a 120-amp alternator that was just ridiculous; I had to change it out.

Since I have an external voltage regulator, it was easy for me to install a simple switch to allow the regulator to be shut off if desired. No power to the regulator=no significant load from the alternator. I haven't found an actual need for this yet, but switching the regulator on and off definitely makes a difference as to how the engine performs. The load from the alternator when the batteries are down a bit is significant.

There are, of course, other engine options out there. For the Daysailor, I'm using a new Vetus 16HP diesel from www.1800runsnew.com. The price, frankly, can't be beat. Stay tuned for more reports about this engine; it's due here in Maine tomorrow. (Hopefully...haven't heard a word since I ordered it!)

That said, I have no intention of using anything but a Yanmar when the time comes to install an engine my Seabreeze in a couple years.

[jhenson]

Thanks for the info. I was pretty sure that I would have to limit the use to the stock 35amp alternator.

Yanmar's are great engines. I own an extra (free) tractor engine (a 3tna-72 18hp with only 300 hours on it). If I could figure out a way to marinize it, I would throw it in there. I know that the transmission on a 2GM would fit it because my brother has a 2GM20 in his boat and the bell housings are the same. What I don't know is if any of their diesel heat exchangers would work with it.

It's a good engine though.

My brother's engine never seems to have any problems.

Joe

[dasein668]

While a larger alternator is nice (I'd sure love one) the stock alternator is really pretty sufficient for the use that most of us put on our charging system. I think the biggest benefit of one of the larger alternators is their lack of internal regulation and thus the ability to use an external smart regulator with multiple stages etc etc. Frankly, I think that a 35amp with an external smart charger would probably suit most people just peachy. (I haven't run any numbers here, just basing it on the fact that my 35 really does a pretty good job keeping up with my load requirements.)

That said, of course, the 80 amp certainly will charge things more quickly, all things being equal!

[Tim]

Actually, the standard alternator on the 2GM20F is 55 amps. And yes, it's more than adequate for most systems. Since I had the opportunity to start from scratch, I elected to try out a more comprehensive charging solution using the external regulator. It's undeniably more complicated overall, however.

[dasein668]

Oops. My bad. We were talking about 35s and that number just stuck in my head...

[The Good Goose]

I have the 1GM10 in my triton and find it very adequate. It has pushed the boat well into 25 to 30 knot head winds. I ran it up the Hudson and champlain canal and it did admirably. Top speed is 5 to 5.5 knots I think the prop is under pitched though so I could get more speed as the engine does not lug down. I use very few electronics and mostly sail. For my needs I would say it is ideal. I don't think the raw water is such a huge deal as there are alot of older raw water cooled diesels out there still going strong. It does vibrate a bit and it is noisy.

If you gave me a choice of my 1gm10 or a 2 cylinder I would take the two cylinder. I don't know the difference in price. For 5 or 6 hudred more I'd take the two cylinder. For a 1000 more I'd probably take the 1gm10. I am a bare bones kind of guy. If I wanted a triton with all the bells and whistles I'd probably go the two cylinder route.

Brock