Replace inboard engine with two outboards?

[bouncycastle]

The new outboards E-Tec are very frugal on fuel but are not cheap so one would be enough. Alternitivly have a old two stroke for the yaught tender . Best to get 10 Hp or 15 HP to push a 28 footer using half power than 6hp at full gas but if your only planning to use outboad in calm water with no tidal currents to fight for short distance to get in out of harbour the 6 HP E-Tec would work well

The 4 strokes use more fuel than the new 2 stroke E -tecs they say but are also frugal on fuel

The old two stokes eat fuel but cheap to fix very little electronics

When or if you sell the 28 foot boat you can take the E-Tec with you should last 20 years easy if you can swallow the repair and service bills that go with modern electronic engines

If your sailor and engine is only for calm conditions the modern E-Tec outboards are the way to

One guy explained he had a big rubber duck and the old two stroke requred two half tanks to go to local island and back
Then he got four stokes and that required 1.8 tanks to go to island and back
Then the E-tec would do the journey on one tank with some fuel to spare all done with same rubber duck at same speeds

The diesel inboards days are largly over

There is 15 hp yanmar outboards diesels but not cheap two cylinder and second hand rarer than hens teeth. It isasically a Yanmar inboard engine in outboard set up and heavy real heavy and not so guite and i think rebranded to something else cant remember the name . There is also the 36 hp version three pot but mega heavy

I saw one conversion where they made well and cut slit for the engine up through the transom seemed the best way to do it so that engine kicked up Others convertions have well and l remove engine and then fit plug to the well when they are sailing to reduce drag

My own 27 sabre boat deep keel 1972 has a SAAB 10hp working easy to fix but i will fit 6 hp old two stoke for back up on transom and to use for tender. Later I might rtremove the SAAB and put in 8 golf cart batterys and do 3 kilowatt eletric engine that can push it at 3 knots using the inboard prop .Later if I can get cheap a second hand diesel generator 12 to 15 hp about 8 kilowatt use that to recharge the battery like a dual power .I can take the tennis out to repair shop to fix it

[Cheechako]

An Evinrude Etec story:
At a boat manufacturer we tested each new boat extensively and also fuel usage before delivery. There was very little difference in outboard brand at all. Of course we were dealing with 200-250 hp outboards, often two on a boat. But Etec, Merc, Honda, Suzuki were all about the same fuel use really.
At that time, 10 years ago, we had a very high failure rate of new Etec engines. Like 20% for a while! It really pissed customers off. Brand new boat, powerhead failed and usually a piston! Those Etecs were wonderful when you got a set that worked though. I really liked the Suzuki 4 strokes.

[captlloyd]

Originally Posted by Pete7

Plus storing large quantities of petrol inboard isn't a great idea. Petrol vapour is heavier than air and will sink down into the bilges and remain there presenting quite a hazard.

Rather than two 6 hp engines, why not use a single 9hp sail drive outboard. The have slightly different gearing and propellers to suit a heavier but slower yacht rather than a light inflatable dinghy.

However, don't make any decisions until you have bought the yacht. Yes you may find an old diesel engine on board, but it might continue to run for another decade completely eliminating the problem. Our Volvo 2003 is 30 years old.

Pete

Absolutely, Diesel engines get rebuilt. For what the op would have in implementing his plan I am sure he could have that small of a diesel rebuilt. ( if it even needs rebuilt). Just go to a regular engine rebuilding shop, not the marina.

[Robert Jansen]

Have you considered an electric outboard? It will be quieter and more efficient than a gas outboard. You can install a (diesel) genset and a battery bank in the space previously occupied by the old inboard.


There is another alternative which you have apparently not considered, and that is to switch over to hybrid propulsion.


In either case, the initial cost may be higher than a couple of gas/propane outboards, but the operating costs, safety, noise and vibration levels are almost certain to be lower, and the new propulsion system will almost certainly be more reliable.

[Talbot]

If you must go the small outboard route, then make sure you get one that is designated as a saildrive. These have a larger propeller which turns more slowly and a larger alternator. Not all manufacturers make them. In fact I am not even sure if there is a 4 stroke version, but the old 9hp saildrive was ideal for use to push a sail boat.


Yanmar made a 27hp and a 36hp diesel outboard. They were purpose built engines and not cut down normal variants. In fact they were handbuilt - one reason that they were so expensive. and they had no cylinder head - it was integral to the main engine block. The 36hp could be uprated to 45hp with a different fuel pump and these were great but noisy engines - tremendous for RIBs, and if they could have made them at a decent cost would have been very popular.

There was an Italian made 15hp diesel outboard - not a good engine by all reports although I have never come across one.

I have seen a much larger diesel outboard which is developed from a petrol outboard. rather than increasing the compression to allow the diesel to work (and probably killing the engine) these have been designed to operate at much lower compression and include a spark plug to initiate the ignition stroke. Not available at the moment due to difficulties in meeting emissions standards.

[LargeMarge]

This may sound wacky... but hear me.

If your project has a genset and batteries, could your outboards be electric?

As I understand the electric outboard concept, the engineers use common lower-legs from Yamaha, Honda, etc.

The power head consists of an enclosed motor with external cooling, in most cases, a radiator or similar heat-exchange.

This might sound nutty... but this's the way we are headed.

[GrowleyMonster]

Originally Posted by LargeMarge

This may sound wacky... but hear me.

If your project has a genset and batteries, could your outboards be electric?

As I understand the electric outboard concept, the engineers use common lower-legs from Yamaha, Honda, etc.

The power head consists of an enclosed motor with external cooling, in most cases, a radiator or similar heat-exchange.

This might sound nutty... but this's the way we are headed.

An electric outboard is indeed viable. However, it is not efficient. Using a diesel engine to turn a generator to produce electricity to charge a battery to power an electric motor to turn a propellor can never be as efficient as an optimized setup of diesel engine mechanically driving a propellor. Never. Can you come close? Sorta. Especially when you need to operate at extremely low power levels at times, and extremely high levels of power at other times, and you factor in the wear and tear on the engine or the need for a variable ratio gearbox and possibly controllable pitch prop. So when extreme maneuvering is the order of the day every day, straight diesel electric can be the way to go. This is why there are so many diesel electric docking assist tugs, dredges, ferries, cruise ships, (most no longer anchor... they use DP to maintain position when docking facilities are unsuitable and passengers must be tendered ashore) and the like. For steady state cruising, it is on the order of twice as efficient to simply couple the appropriate diesel to a prop shaft turning the appropriate prop via the appropriate reduction gear.


Where you can still operate more economically in spite of all the energy conversion losses is when you get "free" energy from the sun or wind or the boat's motion through the water. If you are running a 10kw motor at a 2kw power level and have 2kw of solar charging capability, you can reduce reliance on the diesel genset considerably or even eliminate it completely if you do not motor for long periods. Also, if you only make day trips you can charge via shore power more cheaply than charging with the genset.


For extremely short operation such as docking/undocking and power tacking, efficiency is not the issue anyway. And in this scenario, the freedom from buying fuel, liability of spilling it in the water, cost of upkeeping a diesel engine including perfectly normal wear, the quiet operation of electric, not having a minimum idle speed, instant on and instant torque, ease of maintenance and customization, all point a favoring finger toward electric, even if it is an electric outboard, a definite step downward from a proper electric inboard installation.


The ordinary 12v bank is not what you want for electric drive, though. For small boats you want the highest voltage without going over 50V where there are different electrical standards due to over 50V being arbitrarily considered lethal and under 50V non lethal voltage. If 48V is not enough then smart money goes straight to the 144 to 300V range. Most boats under 35' or so go with 48v and there is nothing to be gained from using lower voltages except trouble. Higher voltage systems are more efficient. A 48v system operated at 5kw requires current of about 100A. A 12V system at the same power level has a current of 400A. Line losses vary with the square of the current. Every wire or cable has resistance. Cable over about 2/0 can be very difficult to work with, and you can't increase the size of the wire in the motor windings, anyway. So you can see how much energy is simply wasted as heat in a low voltage system compared to a higher voltage system. Also let's hypothesize a voltage drop of 2V. This is of little consequence in a 48V system, but is VERY significant in a 12V system. So, the smart money wanting to remain within the "non lethal" electrical codes and standards goes 48v and would never even consider 12V except for a toy.



Electric inboards are fairly simple to set up, and can be inexpensive for a small boat. A 5kw system can be DIY'ed by a knowledgeable person for around $2k using all brand new components, exclusive of batteries. A 10.5kwhr bank can be put together out of 8 6V golf cart batteries bought at Sams Club for $85/each. Add charger for mains charging, inverter for 110VAC appliances, DC/DC converters to eliminate the 12V bank, and you are still in the game pretty cheap. A pair of 300w solar panels and the appropriate MPPT charge controller is a smart addition, and a good base on which to build a bigger solar capability as funds allow.


For the average person who really doesn't feel like learning stuff or is easily intimidated by tech stuff, it makes sense to just rebuild the old diesel, or plop in a new Beta diesel, or hang an outboard on the stern. Alternately pick up a used running diesel but too often you are just inheriting someone else's problem basket when you do that. But I saw a 3cyl Universal diesel of indeterminate age and provenance go for $800 last year, after a run demo bolted down to a bed of 2x12 and railroad ties. It ran, not much smoke, pumped water and didn't leak oil or fuel. It's not unheard of to find a salvaged diesel that is cheap enough that you don't really care if you get 6000 more hours out of it or 600 more hours. Swapping a small diesel really is not that big a technical challenge. The result will be a lot more useful under varied conditions than an outboard.


BUT, an outboard on a transom bracket has a certain Redneck simplicity and appeal. It is right THERE. You can take it off and use it to push your dinghy around. Remove it to take to a shop. Swap it out for a new or newer one in minutes. Depending on your usage profile, the reduced efficiency might not be significant at all. You can get a decent one on sale for $1500 or so, a pawn shop special for $200. (be sure to get a long shaft!) And if you remove the old diesel and put nothing in its place, you have a lot more room below.



A clever shade tree engineer can build an electric outboard. Most such projects involve simply swapping a busted power head out for an electric motor. Turnkey outboards are mostly woefully overpriced IMHO.

[Cadence]

Sorry, some of the posts seem to be out in left field. What was the original question?

[BeachGuy]

Hugo B,

Quick and easy. 1980, 30' Catalina, 11 hp diesel engine. Engine O/H with all related equipment, prop shaft, cutlass bearing and used prop, labor and shipping $12,500 if lucky.

1. 9.9 Suzuki fuel injected, long shaft, 4 blade high torque prop. Engine throttle quadrant with tilt, engine/rpm gauge and control cables and 3 gallon fuel tank. Electric start with 12 volt, 145 watt, 12 amps alternator delivered to my front door. With a 3 year warranty total cost $3102.00
2. Garelick engine kicker plate, 15.5" travel, delivered to my front door, $245.00.
3. Installed by myself. Total cost $3,347.00

38 year old sailboat with a dead engine; what's it really worth. Put a real number down then add either $12,500 or $3,447. If you can justify the price difference then you don't need to be buying or owning a 38 year old sailboat.

75% of power pushes the Catalina at hull speed on 1 liter of fuel an hour. $2.65 a gallon / 3.785 liters = $0.70 cent an hour for fuel and new reliable power and piece of mind.

This is not a blue water boat and won't be sailing in bad weather, or 3 to 4 foot seas, not trying to keep up with the big boats. With millions of gas powered outboards on the water there are no real arguments about gas power outboards installed on a sailboat so that argument is mute.

Great option for old boats, and if not your cup of tea so be it.

Good luck with your decisions.

[Ringmaster]

I would keep looking until you found a boat with a well taken care of in board. I have a 32 year old "yacht" with a 2cyl Yanmar that still runs like a watch. Starts right up, burns no oil and has only needed a few parts really replaced over the years. Parts you would expect to be wear out like a fuel pump, water pump and air filters.

[BeachGuy]

Originally Posted by Ringmaster

I have a 32 year old "yacht" with a 2cyl Yanmar that still runs like a watch.

Just curious what 32 year old "yacht" came new 32 years ago with a 2 cyl Yanmar that wasn't hand build, Yanmar did not produce small marine engines then. It had to be a custom build marine engine for the boat builder. The original Kubota I had in mine let go about 5600 hours. You think maybe it was worn out. Fuel Injectors, Fuel Pump, Exhaust manifold and every related part needed to make to whole packet work. And we are not even talking about a transmission and it's problems. I wish I had video'd the wobble in the wrist pins on the two pistons that came out of it.

My personal experience which 25 year old and older sailboats with original equipment is that it's old, tired and a money pit.

I wish you the very best, I just gave up spending money.

[Ringmaster]

Originally Posted by BeachGuy

Just curious what 32 year old "yacht" came new 32 years ago with a 2 cyl Yanmar. The original Kubota I had in mine let go about 5600 hours. You think maybe it was worn out. Fuel Injectors, Fuel Pump, Exhaust manifold and every related part needed to make to whole packet work. And we are not even talking about a transmission and it's problems. I wish I had video'd the wobble in the wrist pins on the two pistons that came out of it.

My personal experience which 25 year old and older sailboats with original equipment is that it's old, tired and a money pit.

I wish you the very best, I just gave up spending money.

The boat in question is a 1984 Express 30. Kubotas were not known for reliability or longevity like Yanmars. Ask any Laser 28 owner.

[BeachGuy]

Originally Posted by Ringmaster

The boat in question is a 1984 Express 30. Kubotas were not known for reliability or longevity like Yanmars.

Had a Yanmar in my Morgan 33 IO. Bullet proof. This Kubota has left me with doubts as to it maintenance history. But regardless it was shot.

Thanks for the info.

[Richard Hicks]

I have a twenty four foot pilot Cutter with no engine. I mounted a Yamaha 9.9 extra long shaft that has all the bells and whistles, electric start, electric lift. In any wave action you are left wanting as the wheel(prop) comes out of the water. But there is a a company in Ohio who makes an extension for your shaft. They make a 5” extension, and next year will have a 10” extension. This might get you below enough so your wheel will not have cavitation.
Remember your a sailboat so learn to use your sails and motor as little as possible. I’m still learning myself but the upside is the more time on the water practicing the better sailer you become. My best to you. Richard, Father’s Aweigh

[Sailmonkey]

Originally Posted by BeachGuy

Just curious what 32 year old "yacht" came new 32 years ago with a 2 cyl Yanmar that wasn't hand build, Yanmar did not produce small marine engines then. It had to be a custom build marine engine for the boat builder..

Really????
small yanmars for marine use started in 1974

Yanmar Marine Engine Identification Sailboat Supplies, Engine Parts and Boat Parts