teach me about outboards!

[Freebee]

I have never owned a mobo with an outboard always inboard!

I have just acquired a Fletcher Faro 18 ft small cabin. I am thinking 75 -100 hp out board engine. How do I know what shaft length I need? I am thinking a lighter weight engine required to ease the wait on the transom as was not designed for an outboard, so maybe an older two stroke. once its hung on the boat do I need to support the engine weight when its on the trailer?? The boat has an onboard petrol tank so can I use that?? do outboards come with any instrumentation or perhaps a better question what instruments can I hook up, temp gauge oil pressure?

what make of older two stroke if any should I avoid??

anything else i should know??

 

[ShinyShoe]

Hanging 100horses on a transom not designed for it could fatigue it (not just engine weight but the force if 100horses...). Check with insurer.

Yes you can use an inboard petrol tank. But need to think about vents etc. Its much more explosive than diesel.

Instruments... Modern engines can output NMEA2000 an old 2 stroke you would expect revs and temp and probably trim. If its an autolube you'd want to have oil alarm too.

Would be normal to trail with it lifted and in supported other than a lump of wood to hold it up to avoid wear on the lifting bracket.

 

[Beyondhelp]

I have never owned a mobo with an outboard always inboard!

I have just acquired a Fletcher Faro 18 ft small cabin. I am thinking 75 -100 hp out board engine. How do I know what shaft length I need? I am thinking a lighter weight engine required to ease the wait on the transom as was not designed for an outboard, so maybe an older two stroke. once its hung on the boat do I need to support the engine weight when its on the trailer?? The boat has an onboard petrol tank so can I use that?? do outboards come with any instrumentation or perhaps a better question what instruments can I hook up, temp gauge oil pressure?

what make of older two stroke if any should I avoid??

anything else i should know??

75-100hp no problem. You will need long shaft. All Fletchers are long shaft. FYI CHECK THE TRANSOM FOR ROT. At that age more have rotten than have not IMHO. Also, 75hp 4 stroke will be fine. That kind of boat and your intended uses I'd stick away from a 2 stroke as you will just use fuel unnecessary unless you go with a DFI type. (Optimax or Etec for example).

If its 4 stroke outboard, you can use all the same gauges you are used to. If its 2 stroke, then you dont have (or need) oil pressure. The rest is the same.

Depending how old your going avoid Force/Crysler outboards or the Evinrude FICHT (DI) engines. Those seem to fail. Don't hear anything bad except the norm from the rest. Really depends on your budget

Engine doesn't usually need any support. However some put a block of wood between the engine and mounting bracket and trim 'down' on it to keep it tight in the tilted up position. I've never done that though.

The on board petrol tank is fine. If you can drain it out to remove old fuel then fill full and make a note of capacity as it fills with reference to the fuel gauge (if not fitted fit one - there will be a sender somewhere).

 

[VicS]

Check what the maximum recommended power is for your boat. Exceeding that could invalidate your insurance as well as causing weight and handling problems.
but if the transom is not designed for an outboard you may have to strengthen it.
Measure from the transom, or mounting bracke,t top to the water line. Up to 15" will take a standard, aka short, shaft engine. Up to 20" a longshaft, upto 25 " an extra long shaft.
The anti-ventilation plate, aka anti-cavitation plate, above the prop should be about level with the bottom of the transom.
see www.smalloutboards.com/shaft.htm.

When trailing the prop must be covered. The engine may need to be tilted and supported . You should be able to find a support bracket that will fit on your trailer.

No objection to the onboard tank but watch out for the needs of oil injected engines which will also need an oil reservoir .

Tachometer and temperature gauge probably the basics instruments required. You wont need an oil pressure gauge on a two stroke!
All sorts of extra gauges you could fit. Ammeter, voltmeter, cooling water pressure. Some engines are fitted with a pitot tube which can be connected to a speedometer.

Choose one of the major makes. Not in any order of preference. Mercury, Mariner, Johnson/Evinrude, Yamaha, Suzuki, Tohatsu. You should be guided by condition and availability of spares.

You will presumabaly also be looking at fitting remote controls. These are pretty much brand and to some extent model specific.

 

[Freebee]

It was originally petrol mercruiser 3 litre petrol so 120 hp , petrol tank is under the cabin sole, I can see the sender. The boats got a low max value so don't want to over spend on the project but its in good condition for its age I can see the inner transom but ofcourse not the core. I know to do this I am going to have to beef up the transom with some heavy brackets from the inner transom back to the old engine bed.

 

[Lakesailor]

It was originally petrol mercruiser 3 litre petrol so 120 hp , petrol tank is under the cabin sole, I can see the sender. The boats got a low max value so don't want to over spend on the project but its in good condition for its age I can see the inner transom but ofcourse not the core. I know to do this I am going to have to beef up the transom with some heavy brackets from the inner transom back to the old engine bed.

IHmm.
Look at boats with transoms designed to take large outboards, the strength is in the transom. Bracketry to engine beds will not be the answer.
Have you sourced an engine (get all the remotes with it, or you will spend a fortune trying to get the right bits).
It could make a cheap boat into a dear one. People seem to want a grand or so for 70+HP motors.

If it is a 2 stroke with oil injection (Johnson/Evinrude was called VRO) dump it and use pre-mix. Then you know the motor is getting the right amount of lubrication. The concept of variable oil injection doesn't always work on older motors and they can run really rich at low revs. Much easier to revert to pre-mix. It's easy to disable the VRO.

 

[Beyondhelp]

That fletcher would have had a 28mm (if I remember correctly) ply wooden core transom had it been an outboard.

I disagree about removing oil injection UNLESS its proven to failure. Mercury Oil injection with a working oil warning module is perfectly fine and gives you warning of failure. I see to many people removing oil injection as they think they know better than the engine engineers, in some cases it makes sense. But NOT in every.

 

[Freebee]

Beyondhelp that's interesting information because my transom is two layers of plywood possibly 40 mm thick so its quite a bit beefier if your memory is correct

 

[Beyondhelp]

Fletchers don't have big transoms, thats my 17gto which is rated to 150hp. Its hard to say what you would have to be honest. I had to replace mine and used around inch birch ply. IMHO If I did it again I'd over engineer it with two layers of 18. (this is before the gel glassing layers which would add about another 10mm to it.

If just replaced the transom on a 19ft sports cuddy and have gone TOTALLY overkill with that at 3x18mm approved marine ply. That thing is insanely strong now.

 

[Lakesailor]

I disagree about removing oil injection UNLESS its proven to failure. Mercury Oil injection with a working oil warning module is perfectly fine and gives you warning of failure. I see to many people removing oil injection as they think they know better than the engine engineers, in some cases it makes sense. But NOT in every.

The Johnson commercial version of the VRO motor uses pre-mix and not VRO. That tells me what I need toknow. Any 2 stroke motor you can get hold of with oil injection now will be pretty old.
A browse around iBoats forums will give a good feel for opinions.

 

[Beyondhelp]

Thats fair enough for those models but the merc ones are fine - as I said - providing the warning modules are working correctly, and the system is calibrated properly. They lean to 100:1 at idle to 50:1 wot and save a lot of oil with all the other related benefits. (Less smoke no plug fouling etc)

 

[VicS]

The Johnson commercial version of the VRO motor uses pre-mix and not VRO. That tells me what I need toknow. Any 2 stroke motor you can get hold of with oil injection now will be pretty old.
A browse around iBoats forums will give a good feel for opinions.

It's the older versions of VRO that were most troublesome I think. I get the impression that later VRO2 and OMS systems were OK.

Good advice however is to run a newly acquired engine with any form of oil metering on a premixed fuel until it is established that the oil metering works correctly

 

[Beyondhelp]

It's the older versions of VRO that were most troublesome I think. I get the impression that later VRO2 and OMS systems were OK.

Good advice however is to run a newly acquired engine with any form of oil metering on a premixed fuel until it is established that the oil metering works correctly

Yes great idea. Mercury specify that to measure the oil flow and check its all as it should be on their 80-90s oil injected engines.

 

[William_H]

I have in recent years had some use of a boat witha Yamaha 70HP 4 stroke. What a joy a modern 4stroke EFI engine is. No cold start concerns you turn the key it is idling at a precise and regulated speed. You open the throttle and it goes. Pretty much like a modern car. Fuel economy seems to be quite amazingly low.
Now if your is an older boat with an inboard outboard leg then it is quite a common and reasonable modification to remove the inboard enine and fit an outboard on an extended transom/ bracket. This gives you all the space from the old engine for other things and also removes the now much quieter engine further from people space.
A friend had a volvo V8 with contra rotating props and had this changed for a Mercury 250 outboard. The boat is quieter cheaper to run and faster. Plus the ease of lifting and flushing the engine out of the water. All round a good modification. Another acquaintance had the transom fall out of his o/b powered boat due to dry rot. He nearly perished.
So yes modern outboards are good. But do get the transom modified and checked before changing. Yes often people have a prop to support the o/b when on the trailer on the road. good luck olewill