Get-home Engine for 17

Optimizing the performance of Boston Whaler boats
TransFueler
Posts: 18
Joined: Wed Jul 26, 2017 12:19 am
Location: Monroe, WA

Get-home Engine for 17

Postby TransFueler » Wed Jan 10, 2018 8:24 pm

I'm having a hard time figuring out which auxiliary engine to buy for my 1987 17 Super Sport Limited. It has a 2003 Johnson-Suzuki 90-HP four-stroke-power-cycle engine on it, a heavy engine at around 400-lbs. The auxiliary or kicker engine is mostly for a get-home safety factor. We are often on rivers, rocky tidal areas. or just plain remote.

I want to spend under $1,000, and keep the weight around 75-lbs or less.

The reasonable choices appear to be:
    --four-stoke-power-cycle 4 to 8-HP c.2005
    --two-stroke-power-cycle 8 to 15-HP 1998 and newer typically
Understandably, none of these engine will reach more than roughly hull speed. We get a fair amount of wind and wave action here, and I want to be able to hold hull speed, even uphill and in choppy water.

Recommendations, advice, sage counsel appreciated.

Ed
1987 17 Super Sport Limited
2003 Johnson/Suzuki 90 Four Stroke EFI

Jefecinco
Posts: 662
Joined: Fri Oct 09, 2015 6:35 pm
Location: Spanish Fort, AL

Re: Get-home Engine for 17

Postby Jefecinco » Thu Jan 11, 2018 10:24 am

A 2003 Suzuki four stroke engine should be very reliable. Has it failed? Stopped running? Failed to restart after stopping?

My reading leads me to believe most four-stroke engine failures are due to problems with fuel, such as water in the fuel, old untreated fuel, deteriorated fuel lines and bulbs, running out of fuel, etc.

An aftermarket water separating fuel filter such as marketed by Parker/Racor installed in the fuel supply line between the primer bulb and the engine can be a very effective tool to prevent fuel related problems.

Ensuring the rubber fuel hose components meet current USCG standards will also help. Engine OEM primer bulbs are often more reliable than aftermarket units.

Electrical engine cranking systems are another frequent culprit. A boat with two reliable batteries and a good switching device can prevent most cranking problems. For reliability AGM batteries are recommended.

On the water towing insurance is available in many areas. If all else fails they can get you home.

The point of all this is that the cost of a second engine and its maintenance, as well the added complexity, can probably be avoided by ensuring your boat has an updated fuel and electrical system. If reliability remains a concern, the cost of another engine can be avoided by tow insurance available for your boating area.
Butch

TransFueler
Posts: 18
Joined: Wed Jul 26, 2017 12:19 am
Location: Monroe, WA

Re: Get-home Engine for 17

Postby TransFueler » Thu Jan 11, 2018 2:54 pm

All good points, Butch.

In my case, we have experienced engine failure, in a location with no towing service. The concern was on a recently purchased Whaler; water in the fuel. Since that incident, I've replaced all fuel lines, all filters, and added a Racor water separator. The boat has two batteries, which is always a good idea.

I also have a handheld VHF aboard, and of course a cell phone. We travel mostly lakes and rivers with this boat, occasionally Puget Sound. On the lakes and rivers there is no SeaTow access, only fire and police emergency services. They frown on calling them for a simple breakdown, unless you're in the water and in trouble.

So, again, I'm seeking input on the right kicker, or get-home engine.
1987 17 Super Sport Limited
2003 Johnson/Suzuki 90 Four Stroke EFI

ALAN G
Posts: 8
Joined: Sat Oct 17, 2015 10:57 pm

Re: Get-home Engine for 17

Postby ALAN G » Thu Jan 11, 2018 4:46 pm

Transfueler--I believe you have accurately identified the reasonable choices and horsepowers. To bound your choices and confirm, I offer my experience on my 1975 Revenge 19.

My boat is heavier and has more windage and hydrodynamic drag than yours does. I have had a 9.9=HP two-stroke outboard since the boat was new in 1975, first a Johnson, then an Evinrude. A 9.9-HP is adequate in all sea conditions and wind conditions I have experienced, and we have used it extensively for trolling. Normally we operate at about two-thirds-throttle to move the boat at 5-nautical-miles-per-hour. [Boat speed] will max-out at 6-nautical-miles-per-hour depending on boat load and wind. I consider [a 9.9-HP engine] a great choice for my boat; it weighs 72-lbs.

Although the current engine, a 1985 Evinrude 9.9, is adequate, the same engine is also available in a 15-HP version. I run a lower pitch 9 x 9 propeller to get the [engine speed] up to where it needs to be for proper power output and thrust.

Of course this engine is larger than what you need on your 17, so I would consider it an upper bound. Since you are using the engine mostly for get-home safety factor, you probably can get by with less weight and lower horsepower. And 1980-and-later engines in the same power and weight range are widely available, are easy to fix, to overhaul, and are very dependable.

As a lower bound, 4-HP is probably too little for you. I have a classic wood 16-foot Lyman lapstrake runabout. I carry an 1974 Evinrude for emergency power. The engine is so light--35 lbs--I don't even keep it on the transom. I carry it inside the boat and when I want to use it I put it on the transom. I run it every trip to keep it fresh and operable. It will push the boat at 4-nautical-miles-per-hour at full throttle with a standard right angle drive lower unit (as opposed to the weedless lower units also available on the old 4's) and run an 8 x 4.5 three-blade propeller. These engines were produced in models called Lightwin and Yachtwin versions, with the latter intended to push sailboats. They tend to have longer shaft lengths (20 or 25-inch) in addition to the standard 15-inch shaft. Such a 4-HP engine might be enough to get you home but has no reserve power.

I think 6 to 8-HP would be a good target to satisfy your criteria. I don't own an outboard in this range but there are many. A close friend had an 8-HP Honda on his 23-foot sailboat; it was a wonderful engine. The sailboat hull is much more hydrodynamically sleek than your square transom hull but it would push the sailboat in all conditions of wind and waves on San Francisco Bay, and full power was never needed. It is a relatively heavy engine though at close to 100-lbs.

Final miscellaneous thoughts: being as how this is a backup engine, I would recommend a two-stroke engine due to its light weight, ease of maintenance, and ability to be stored in any position without losing crankcase oil. If you were going to troll with it and use it more extensively, I would then recommend a four-stroke for its clean smelling exhaust. If you do go with a two stroke, you will need an auxiliary gas tank because the fuel will likely have to be pre-mixed with oil. Running a four stroke main engine is no [problem]. I now run a Honda 135. If you carry extra two-stroke oil, you can mix it aboard if extra fuel is needed. All you have to do is make sure you have a good, safe way of moving unmixed fuel from your four-stroke tank to the auxiliary two-stroke tank if you need more than the auxiliary tank carries to get you home.

I, too, have been let down by a main engine failure. While crossing Green Bay, Wisconsin from Marinette to Sturgeon Bay, the head gasket failed on my 1985 Evinrude 150 causing the engine to overheat. The 9.9 brought us safely in from the middle of Green Bay.

Al

TransFueler
Posts: 18
Joined: Wed Jul 26, 2017 12:19 am
Location: Monroe, WA

Re: Get-home Engine for 17

Postby TransFueler » Thu Jan 11, 2018 6:21 pm

Excellent info. Thank you, it's appreciated.

Ed
1987 17 Super Sport Limited
2003 Johnson/Suzuki 90 Four Stroke EFI

Whal
Posts: 22
Joined: Thu Jan 14, 2016 7:11 am

Re: Get-home Engine for 17

Postby Whal » Thu Jan 11, 2018 7:05 pm

I have a 1999 Alert 17--same hull as the Montauk 17--and I boat exclusively on Lake Erie. I have a Tohatsu 6-HP Sail Pro kicker on my boat. It will push my boat to 6.1-MPH with my main engine in the down position and 6.3-MPH with the main engine raised. I have had this engine on for three seasons, and I am very happy with it.

The Tohatsu weighs only 59-lbs. Before I got the Tohatsu, I had a Mercury 9.9 two-stroke-power-cycle engine that weighed 81-lbs and would push my boat 6.4-MPH. So 6-HP is all you need.

I have been in some snotty seas on Lake Erie with my boat, and am extremely satisfied with the 6-HP.

Try to go as light as you can with your auxiliary engine. The Montauk 17 hull is very sensitive to too much weight on the stern. My personal preference is to try to keep total [transom] weight as close to 320-lbs as possible. I learned this from personal experience.

From experience, do not use a bracket; mount your auxiliary engine directly on the transom--it is more solid. My auxiliary engine is mounted on the port side.

Tohatsu also makes the Mercury 6-HP. It's the exact same engine painted as a Mercury.

TransFueler
Posts: 18
Joined: Wed Jul 26, 2017 12:19 am
Location: Monroe, WA

Re: Get-home Engine for 17

Postby TransFueler » Thu Jan 11, 2018 8:57 pm

Thank you. Yes, our main engine is already heavy at around 400-lbs.

There is a Sail Pro 6 on my local Craigslist, think I'll go look at it.

I moved the batteries and fuel tanks farther forward for better weight balance. The prior owner had a sand bag in the bow locker. Now I know why.
1987 17 Super Sport Limited
2003 Johnson/Suzuki 90 Four Stroke EFI

jimh
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Location: Michigan, Lower Peninsula
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Re: Get-home Engine for 17

Postby jimh » Thu Jan 11, 2018 10:16 pm

The total transom weight should be your biggest concern. Since you already have a heavy 90-HP engine on the transom, choose your get-home engine to be as light as possible.

Whal
Posts: 22
Joined: Thu Jan 14, 2016 7:11 am

Re: Get-home Engine for 17

Postby Whal » Fri Jan 12, 2018 6:42 am

TransFueler--the Tohatsu Sail Pro comes with a high-thrust propeller and an alternator; the regular Tohatsu 6-HP engine does not have those features.

jimh
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Re: Get-home Engine for 17

Postby jimh » Fri Jan 12, 2018 1:15 pm

Regarding whether a 9.9-HP or a 15-HP engine would be best for a get-home engine on a 17-footer:

I used to sail once a week with a fellow on his 25-foot sailboat. The auxiliary engine was a 15-HP outboard. The owner regularly cursed the 15-HP and the decision he made to buy it instead of the 9.9-HP version (for the same price). The 9.9-HP version was designed for pushing boats at displacement speeds. The 15-HP version was tuned for running at full throttle and going a lot faster. It was always fouling plugs, reluctant to start, and smoked a lot. It clearly did not like to run at the low engine speeds it was getting when pushing around a 25-foot sailboat at 5-MPH.

The best auxiliary for a 17-foot boat is a small outboard that will be running at a sweet spot in its power curve, probably about 2,500-RPM and not be lugging under too much load from the propeller due to the pitch being too high.

My friend John had a an OUTRAGE 22 that he fitted with an auxiliary engine. He described the installation in detail in an article that I published in REFERENCE. See

Mounting a Yamaha T8 Four-Stroke Auxiliary
On a 1992 OUTRAGE 22 with Evinrude 225-HP Main Engine

by John Flook
http://continuouswave.com/whaler/reference/yamahaT8Kicker.html

John said that the auxiliary engine, with its high-thrust propeller, actually was better for maneuvering the boat at slow speeds in reverse than the main engine.

TransFueler
Posts: 18
Joined: Wed Jul 26, 2017 12:19 am
Location: Monroe, WA

Re: Get-home Engine for 17

Postby TransFueler » Fri Jan 12, 2018 2:01 pm

I think most 9.9 and 15-HP outboards share the same engines with the exception of the carburetor and maybe a couple other minor things--same block, same pistons. I guess it makes sense that the bigger carburetor might not be happy running at a lower load, but that much difference?

The finicky nature of modern small outboards seems a bit crazy. If these were automobile engines, we would go nuts on the manufacturers and dealers. If my Chevy 2500 turbo-diesel pickup had running [problems] because I drove it slowly; without my big, enclosed, car trailer behind it, that would not be acceptable. I wouldn't go buy a little V6 F150 for the lighter loads. My Yamaha 125 scooter is perfectly happy putting around the pits at the race track, or zipping along at top speed.
1987 17 Super Sport Limited
2003 Johnson/Suzuki 90 Four Stroke EFI

jimh
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Re: Get-home Engine for 17

Postby jimh » Sun Jan 14, 2018 1:44 pm

Attempting to use two engines, one which runs directly from gasoline fuel and another that requires its fuel be a pre-mix of gasoline and two-cycle oil, is going to be a long-term nuisance. There are two solutions to this problem:

--maintain separate fuel tanks for each engine; the drawback is the tanks cannot be cross-connected. Certainly the engine that needs pre-mixed fuel must never be run from the gasoline-only tank; the other engine could be run from the pre-mixed tank, if needed, and probably no permanent harm would occur.

--maintain a separate tank for only two-cycle oil, and install a pre-mixing device that adds oil to the gasoline supply for the engine that needs the pre-mixed fuel; there once were such oil-gasoline mixing devices available. I don't know if they are still being made.

The drawback of both methods is the requirement for a second tank. This cannot be overcome without changing to different engines.

There is a general problem in providing fuel supply to two engines from one tank; this must also be overcome. On the other hand, having two fuel tanks that are completely separated and isolated adds to the redundancy of the get-home engine. The need to run the get-home engine may be due to fuel contamination in the main engine's fuel tank. A separate fuel supply for the get-home engine allows it to run even if the main tank fuel is contaminated or the main tank and its fuel hoses are damaged in some manner.

If two engines are to be fed from one fuel tank, there generally must be a check valve each fuel hose to each engine that will prevent backflow of fuel. The typical fuel hose in-line primer bulb does provide a check valve, but the effectiveness can be compromised if the primer bulb is not always oriented vertically. The problem occurs when only one engine is running. The running engine's fuel lift pump tries lift fuel from the fuel tank to itself, but it can also cause fuel to backflow out of the fuel system of the non-running engine. This can be a problem if the running engine's rate of fuel flow is quite high, and its lift pump is developing substantial suction. It can occur that the lift pump of the running engine will pull fuel from the non-running engine's fuel system. This can also lead to the possibility of air being introduce into the fuel system.

The problem is generally avoided when both engines are running. If only one engine is to be run at a time for long periods, it may be useful to install two shut-off valves, one in the fuel line to each engine, so that there is no possibility for backflow of fuel from the non-running engine to occur.

TransFueler
Posts: 18
Joined: Wed Jul 26, 2017 12:19 am
Location: Monroe, WA

Re: Get-home Engine for 17

Postby TransFueler » Mon Jan 15, 2018 2:21 pm

I think that a two-stroke-power-cycle auxiliary engine is better in my scenario. My thoughts are to either simply have a small, maybe three-gallon, fuel tank for premix or buy an engine that has automatic oil mixing, such as a Suzuki.

Considering that my last engine failure was caused by water in the fuel tank, a separate small tank is probably the way I'll go.

My neighbor has two Yamaha four-stroke engines on his boat, both the main and auxiliary. He simply switches the fuel line from one engine to the other, and draws from a single tank. Much simpler than running two separate fuel lines and valves.
1987 17 Super Sport Limited
2003 Johnson/Suzuki 90 Four Stroke EFI