Re-powering a Classic 17-footer

[Kolbert]

I am in the final stages of deciding on an engine to re-power a classic 17-footer. A c.1995 Johnson 90-HP VRO is to be replaced--it has served me well. [In a later post the author corrects the age of the engine to be a 1986 model.--Moderator]

The classic 17-footer uses a 20-inch-shaft engine. I will need to repair the transom holes that were for the blind mounting bolts, and drill new transom hole for engines without blind mounting bosses. I want the new engine mounting height to be two-holes-up. I plan to buy a used outboard engine. I will be installing the engine myself.

Q1: what pitfalls should I keep in mind when looking at used outboard engines?

Give any other comments related to re-powering a classic 17-footer.

[Phil T]

For re-powering a classic 17-foot hull, my choices, in order, are:

1. a Yamaha F70, which has the best power to weight ratio, good reliability, and good performance;
2. a Suzuki DF90--a great engine at a competitive price; and
3. an Evinrude E-TEC [90], but it would be my first-choice if it were still being manufactured. (Alas, private equity ownership strikes again).

[jimh]

For help in the location of the engine mounting holes when faced with a shallow engine splash well, see the comprehensive advice on choices in the article at

Transom Mounting Hole Layout for Shallow Splash Well
https://continuouswave.com/forum/viewto ... f=7&t=5808

In particular, pay attention to the paragraph that begins, "If the lower pair of transom holes is spaced 6.50-inches as shown by the green holes in the diagram..."

[jimh]

Because your existing engine is a 90-HP, and I suspect that engine was a V4, I would anticipate you will want to re-power with another 90-HP engine. I believe the specification weight for the V4 90-HP engine was 301-lbs. That weight would be a good number to keep in mind when looking at more modern 90-HP engines. I think you will find most modern 90-HP engines will weight more than 301-lbs.

If the new engine causes the boat to have a static trim with the engine splash well drains below the water line, you should give some thought to moving the engine's cranking battery out of the stern and into the area inside the console on the deck. This will require new battery cables of longer length and a larger wire gauge, probably at least 4-AWG (if only 10-feet or less) and perhaps 2-AWG (if longer than 10-feet).

You should also consider the possibility of being able to re-use some of the existing engine rigging, such as electrical harnesses, ignition key switch assemblies, remote throttle and shift controls, warning lamps, warning horns, engine gauges, and so on.

With your Johnson engine from the mid-1990's, the wiring harness MIGHT be the newer style MWS harness. That harness was introduced about 1996, and it was kept in use until Johnson-Evinrude ceased production.

I don't have a clear indication that you want only a modern engine, that is, only a four-stroke-power-cycle engine or a two-stroke-direct-injection engine (like an E-TEC). Depending on how many hours you are able to use your boat, you might be able to tolerate buying a classic two-stroke-power-cycle carburetor engine, maybe just a more recent model of your Johnson 90-HP.

I know gasoline has become much more expensive than it was 30-years ago, but if you only consume a modest amount of gasoline fuel each boating season, the costs saved by reduced fuel consumption may take several decades to offset the greater cost of a modern engine.

The E-TEC 90 engine is a very nice engine. The problem if finding an excellent used E-TEC 90 is that most owners are very happy with them and are not selling them.

[Kolbert]

When looking for a used E-TEC engine, the ones that I have checked out are being sold with side mount controls, not with the top-mounting controls that a [center console boat] would require.

I do not see any way to convert the side mount remote throttle and shift control into a top-mount throttle and shift control

Also, my current Johnson controls ARE NOT properly setup to use, and as it turns out my engine is actually a 1986 model, not a 1996-model.

I found a top-mounting control for sale on an web auction site: https://www.ebay.com/itm/395019323918

[jimh]

With the significant change in the manufacturing epoch of your present engine to become ten years older than previously described, the 1986-era engine wiring harnesses you now have will not be useful if you were to purchase an E-TEC engine. The E-TEC uses the MWS type wiring harnesses, which were introduced c.1996. A c.1986 OMC engine would use a much different type wiring harness with a large, red, rubber, Amphenol connector on the engine and the mating connector on the remote control wiring harness. The electrical connectors were not directly compatible, but with some adaptors to account for the much different connector styles, an older harness could be made to work. But you would need to find the OEM adaptor rigging kit to make it possible.


As for the mechanical cables and the shift and throttle linkage, they should be useful with an E-TEC, as I do not think there was substantial change. For example, when I re-powered with an E-TEC I was able to use the c.1992 mechanical cable top-mount control I had for the shift and throttle connections.

You assessment of the inability for you to convert a side-mount shift and throttle control into a top-mounting shift and throttle control is correct; you cannot convert a side-mount control to a top-mount control in any reasonable fashion or form, and trying to do so would be useless.

[jimh]

I found a top-mounting control for sale on an web auction site: https://www.ebay.com/itm/395019323918

That item is priced as a very attractive bargain, and it looks like an actual Evinrude OEM product. The connectors associated with that top-mount control are the MWS type used by the E-TEC. For installation on your older boat, you would need to purchase the MWS type wiring harness, or, if you planned to convert all engine instrumentation to the NMEA-2000 gauge type, you would need to purchase an I-Command wiring harness.

IN CASE YOU ACTUALLY DECIDE TO BUY AN E-TEC

If you eventually purchase an E-TEC engine, more advice on rigging an E-TEC engine can be found in a two-part article series, "E-TEC RIGGING NOTES," which I wrote when rigging an E-TEC engine on my boat. The article series begins at

https://continuouswave.com/whaler/refer ... gging.html

A second article "Advanced E-TEC Rigging" is found at

https://continuouswave.com/whaler/refer ... anced.html

In the MARINE ELECTRONICS and ELECTRICAL forums, you can also find a very large collection of articles on E-TEC rigging for instrumentation with the the Evinrude I-Command, ICON Pro, ICON Touch, and NAUTILUS series gauges:

https://continuouswave.com/forum/viewforum.php?f=10

I don't have much more general advice to offer to you about re-powering your classic 17-footer.

[msteinkampf]

If you want the short answer, just read Phil T's post. Here is a longer answer: it depends on ...

1. What you want to do with the boat. If you are routinely pulling a slalom skier out of the water, stick with a 90 HP, or even a 100 HP if it's the same weight as the 90. If your boat is mostly used for fishing or pulling water toys, you should be able to get by with a 70 HP motor; I wouldn't go below that.

2. How old a motor you are willing to consider. A 90 HP Yamaha 2-stroke is widely considered to be an excellent choice for a classic Montauk 17, but they were no longer sold in the US after 2010. Mercury 90HP 2-stroke engines were no longer offered after 2005. These engines are fairly simple designs that can be easily maintained, but they are noisy, smoky, and use more gas than the newer 4-stroke engines. Personally, I would pass on the E-TEC, whose manufacturer abandoned the technology and later the outboard motor market entirely, but there are fans.

3. How important added weight on the transom is. Classic Montauk 17s were designed for lighter 2-stroke engines that are no longer marketed. A new 90 HP Suzuki weighs 343 lbs, a Yamaha 353 lbs, and a Honda (and Mercury) 359 lbs. Those engines have been installed on many Classic Montauk 17 boats, but they do result in the transom riding lower in the water. Personally, I wouldn't consider these engines unless I was willing to move the batteries to the console. On the other hand, a 70 HP Yamaha weighs only 253 lbs. (These weights come from the manufacturers' websites.)

4. How much you need the additional features of a larger engine. I am thinking mostly about alternator output, which is 27 amps for the 90 HP Suzuki, 35 amps for the Yamaha and Mercury, and 44 amps for the Honda. The 70 HP Yamaha alternator output is only 15 amps.

5. Other factors such as dealer availability and how much you are going to use the service manual. I have never seen this mentioned in online discussions, but the quality of the service manual does matter to me. I have the factory service manuals for a 1991 Mercury 90 HP and a 1995 150 HP Yamaha, and the quality of the Mercury manual is much higher, with many photographs and detailed instructions that are missing from the Yamaha manual. I can tell that the Mercury manual was written in English, but the Yamaha manual is a translation, presumably from the Japanese.

When I bought my Montauk 17 in 1990, I was considering a 70 HP engine, but I was advised to get a 90 HP. That was good advice, as my 1991 90 HP Mercury weighs 280 lbs, the same weight as the 70 HP model. Nowadays, the situation is different. Mercury doesn't even make a 70 HP outboard, and the 75 HP and 90 HP units are much heavier than my current engine. As Phil T noted, the clear winner in the power-to-weight ratio is the Yamaha 70 HP, and this motor has a good reputation for reliability. When my 90 HP Mercury gives out, it is what I'll be buying for my Montauk 17, a boat primarily used for fishing that doesn't require a high-output alternator.

M