Outboard without external tank - thoughts?

[slawosz]

Hi,
I am looking to buy 5 HP (probably 2 stroke) engine, which would give my boat proper push. Its 'high thrust' version, but it does not come with external tank connector, so I would need to rely on internal tank, which is I believe around 1.2 liters, so I believe its would give me like 30 minutes of running. I need larger engine, so I could plan longer (up to 10 hours sailing) trips, and I am thinking if having to refill tank during longer period of motoring wouldn't make me mad. Also, could be quite unpleasant during motoring during choppy water. What do you think?

 

[Akestor]

I think that would be a problem...you could have rain while refilling, a wave splashing and seawater getting in the tank, or spill the gasoline outside the motor as the boat moves...

 

[Mark-1]

I've got a 5hp 2T mariner. I fill the internal tank every 45mins or so. It's tolerable, and by definition the OB is used in calmer conditions.

However, I have an external tanks connector and this season I will be finally getting a tank to save me clambering about over the back of the boat. Should have done it years ago.

Have you considered retro fitting? It's pretty easy to fit an external tank connector. You just need a t-piece in the fuel line the carb side of the fuel tap with the connector attached.

 

[LONG_KEELER]

As above . Two strokes can be quite thirsty at high revs for 5hp.

Retro fixing a tank recommended .

 

[Adios]

I thought everything 4HP and up has a connection for an external tank even if it also has an internal tank? Pretty sure you'd get more than 30 minutes though anyway but its a bad idea to have to refill an outboard at sea even every hour.

However if you do need to I highly recommend getting a FuelFriend 1.5l tank with one of their rigid spouts and filling that up inboard and transferring it into the engine which is then possible with one hand.

 

[slawosz]

Thanks for anwsers. I always have 3 x 1l mixing bottles with me with mixture, so refilling is easy, but to be honest, I never had to use engine for longer than 30 minutes, so never had an issue with refueling. Currently using 3.3 HP which is ok, but I know its too weak for serious motoring.

Regarding retrofitting, I was thinking about it, even found proper connector on Ebay, but was wondering it this would work. I don't know if external tank engines have pump instead?

 

[LONG_KEELER]

Thanks for anwsers. I always have 3 x 1l mixing bottles with me with mixture, so refilling is easy, but to be honest, I never had to use engine for longer than 30 minutes, so never had an issue with refueling. Currently using 3.3 HP which is ok, but I know its too weak for serious motoring.

Regarding retrofitting, I was thinking about it, even found proper connector on Ebay, but was wondering it this would work. I don't know if external tank engines have pump instead?

Small outboards 2T have a pump which is an integral part of the carburettor or stand alone before the carb. They are not driven by the engine directly but work on suction . You can spot them by a square shape normally . Some work on gravity from the integral tank and don't have a pump.

You still have to prime the external tank prior to starting by hand squeezing the bulb on the fuel line.

 

[Sandro]

My boat is very small, to me a standard external tank is too big and the tubing a nuisance. On the other hand of course pouring fuel from a heavy tank on extended arms in a lively boat in a short chop is all but pleasing.
I made this pressurized tank.

It remains on the floorboards. For refilling, the hose end is fitted into the OB tank input, the wire spring holds it in, you pump the air in and open the fuel tap (right hand in the picture). Refilling keeps on all alone, just watch for overflow.
The other tap shuts the air input and vents the tank after refilling.
Due to the season and Covid moving limitations I did not yet test the tank on board but it is the updated copy of one I made as a young boy with a military 20 litre jerrycan and a motorscooter tire pump which worked very well.

Next job would be a valve that stops the flow before overflowing but I think I'll never tackle this for sake of "keep it simple".

The tank is mild steel 5 litre salvaged floating on the lake many years ago. The size is good for my motoring.

 

[Adios]

Thinking about it the best thing anyone can do is strongly advised against that outboard that doesn't have a proper secure reliable external tank fitting.

One of my first experiences of boating was on my brothers boat with a 2 stroke twin that kept being dunked as the boat pitched until it was running on one cylinder and then no cylinders. Then drifting beam on towards the massive steel wall of a ship moored at Felixstowe docks while we failed to get it running again. The harwich harbour launch saved us just in time.

I did have a light weight trailer sailor with an outboard and dinghies but they were all very light and were lifted quickly by any wave so the outboard wasn't dunked by a delayed pitching motion that might occur in a heavier and finer lined boat like yours. I'd really only feel an inboard was right for the job but clearly people do managed with outboards on them. But at the very least you must have a reliable fuel system that will run for hours and be able to be refilled in the cockpit if needed. Hanging over the transom and trying to refill is dangerous and likely to get water in the tank. When to refill it will be something else to remember, you'll either be refilling it more often that you need to or it will be running out at which point water will be splashing up into it around the air intake and spark plug as you put all your weight over the transom pushing it down. Repeat every half an hour or so for 10 hours or 30 hours. If its really only 30 minutes on a tank that trip you were planning could mean 30 or 40 refills including at night. (ok in theory you'll be sailing if there is wind and if motoring it will mean there is a dead calm - but you want the option) It might hold you back soon when you want to do more ambitious passages and you'll regret not getting a different engine. Honestly its a very bad idea. Bodging a fitting onto it as well might work but won't be as reliable as just finding the right engine in the first place.

Keeping everything together when the weather turns nasty or something goes wrong is often helped by using the engine especially with inexperienced sailors, needing to refill the tank at that point will be very very unwelcome.

 

[KompetentKrew]

Find the manufacturer's exploded parts diagrams for it - you can probably get the parts to convert it to remote fuel tank for not much money.

There are considerable savings to be had by buying outboard fuel tanks secondhand - check Gumtree, FridayAd etc.

 

[MADRIGAL]

I have a 2.5 hp 4-stroke Yamaha with an internal fuel tank that gives me 45 minutes running time at 4 knots. As suggested above, I don’t need to run it for long in big seas as in that case there is usually also wind. Nevertheless, refuelling from a jerry can while hanging over the transom is no fun, and carries all the risks mentioned in other posts. I have heard that there are small bottles designed for camping stoves that might make a good alternative to the jerry can and funnel method.

 

[VicS]

Thanks for anwsers. I always have 3 x 1l mixing bottles with me with mixture, so refilling is easy, but to be honest, I never had to use engine for longer than 30 minutes, so never had an issue with refueling. Currently using 3.3 HP which is ok, but I know its too weak for serious motoring.

Regarding retrofitting, I was thinking about it, even found proper connector on Ebay, but was wondering it this would work. I don't know if external tank engines have pump instead?

What engine are you considering . Its very unusual for a 5 hp 2 stroke not to have provision for a remote tank. I cannot identify one.

The difficulty in modifying an engine without provision for a remote tank may be adding a fuel pump if one is not already fitted.

 

[DownWest]

If buying a new engine, unlikely to be 2T? and the OP does not say off the transom or in a well. The quick take on this is 1 lt bottles with spouts. for the odd time he actually needs to refuel on the move.

 

[Adios]

If buying a new engine, unlikely to be 2T? and the OP does not say off the transom or in a well. The quick take on this is 1 lt bottles with spouts. for the odd time he actually needs to refuel on the move.

I assumed its off the transom on an Achilles 24 but I just googled and found this one with a well which would change everything. @slawosz ?



But I don't think he should assume it will only be occasional times. He was talking about long passages before. Better to picture the need in a worse case scenario, sail slide jammed or some other gear failure, can't sail, weather worsening, need to get in against the tide, 5 hours flat out motoring in significant seas needing to open the tank 10 times while hanging off the back. Or motor repeatedly running out of fuel and being sloshed with water while its refilled. It seems like a bad idea if its on the transom. Fine if its sitting in the cockpit like this though

 

[Adios]

This achilles 24 its on the transom. Seeing how far back it is from the helm can imagine its interesting manoeuvring that in marinas

 

[slawosz]

Thanks. So my Achilles 24 has cockpit well, I wouldn't really get one with a transom mount. Those are inboard versions with inboard removed. Engine is very accessible, in perfect place to drive the boat and very, very noisy. I have well plug, so most of the time (unless sailing with family) I remove it and have 'real' sailboat Thats one of the reason I don't want 4T - they are bad for storing, although might buy one.