Should I be concerned? Towing a boat.

[Bilopete]

I was out on the Rocky barrage this afternoon when I got waived down by a broken down boat. They asked for a tow back to the ramp and naturally I agreed.

My boat is 4.3M stacer with a 2st evi on the back. I was alone so there wasn't much weight in the boat.

The boat I was towing was a brand new 5. or 5.5m stacer with 3 fairly large guys in it.

The distance was only about 2klms and I sat on 5-6 knots but after I I dropped them off, I went for a quick run and about 5 min later the engine accelerated, deaccelerated, accelerated and finally conked out - like it was running out of fuel.

I still had a 1/2 tank of petrol but the boat hasn't been out for a month or two so the petrol is a bit old.

It restarted again 5 min later and I finally got back to the ramp at about10-15knots.

When I got it home, I tried kicking the motor over and 1t started 2nd pull.

Is there any chance I could have damaged the engine as a result of towing?

If its any consolilation to me, the operator of the boat was from Terry's Marine and offered me a free service for helping out.

So, should I be concerned?

Secondly, what - if any - is the etiquet in this type of situation?

Cheers

Pete

[FNQCairns]

Yes lot's of 2 strokes need rebuilds after towing, being lugged for so long raises piston crown temps through the roof. The rings score the bore and or catch an exhaust port snap and bingo thousands in damage.

Not saying this is your problem just that the coincidence is a little scary as this form of blow up is not uncommon.

Pull your plugs and look for aluminium on the electrodes or even damaged electrodes.

Good luck!

cheers fnq

[Bilopete]

You've got me worried now fnq!

Should I be operating the motor at all or take it straight in for a service?

Pete


Yes lot's of 2 strokes need rebuilds after towing, being lugged for so long raises piston crown temps through the roof. The rings score the bore and or catch an exhaust port snap and bingo thousands in damage.

Not saying this is your problem just that the coincidence is a little scary as this form of blow up is not uncommon.

Pull your plugs and look for aluminium on the electrodes or even damaged electrodes.

Good luck!

cheers fnq

[ozscott]

I would take it to a service centre ASAP. I had a mate with a 150 black max merc - bit old, but he towed for 5 mins with it at about 3000rpm and fried a piston...2 strokes dont like lugging as FNQ said.

I wouldnt have known about this a while ago, but its a real problem. Let VMR tow people - if their life is in danger stick them on your boat, but dont tow them unless its a 20 metre tow and you just stick her in fast idle only.

Cheers

[FNQCairns]

Pete, lots get away with it too!

Your fuel was old so that counts against you as well, still it could all be a coincidence with a fuel or electrical gremlin somewhere else just complicating things.

So I dunno what you should do, without a compression check as second even if the plugs look OK.

Depending either it will all be a red herring or you could do more damage running it again and causing greater rebuild costs, if a rebuild is an option on your engine (would make a good excuse to get the funds passed for a new one if yours is old:)).

I will only tow someone for imminent safety purposes (nor do I expect a tow), have a VHF and will contact those setup to do it properly if needed, the risk of damage is simply too great when abusing an engine this badly for such a long period.

cheers fnq

[Hornet Rider]

Yes lot's of 2 strokes need rebuilds after towing, being lugged for so long raises piston crown temps through the roof. The rings score the bore and or catch an exhaust port snap and bingo thousands in damage.


cheers fnq

fnq, what is lugging & what are the causes? Over propped, insufficient revs for the load? I googled it with lots of hits but no explanations or what causes it.

cheers

[tigermullet]

I hope it turns out okay for you. Towing larger boats over a distance is a real problem, as others have said. That's how an older merc was shagged many years ago. These days, I won't attempt it unless there is the need for an urgent tow and the other boat or persons are at risk.

Fnq and Ozcott are very right. But, once again, here's hoping you have avoided damage.

[ozscott]

mate - 2 strokes are not torque monsters - they work best when revving hard and getting their power. There is a lot of gudgeon pin pressure when using them like a tractor and heat problems. You cannot get the answers here without checking the motor, but it does not sound too flash.

Cheers

[tigermullet]

The problem with towing is that the motor is, essentially, over propped. Much the same as having too large propeller pitch and not being able to operate at wide open throttle within the rpm range specified for the motor. That is if you can get only 4000rpm out of a motor that is designed for max rpm between 5000-5500 you are either overpropped or overloaded by weight.

If over propped, the engine will be 'loaded up' across the entire range causing, the engine will struggle etc., - all the problems that Fnq and Ozscott have mentioned. Trying to tow a larger, heavier boat should only be done at very slow speed and for only a short distance.

I wish I had known that before blowing up the old merc. However, there is still a chance that you have gotten away with it and all will be well.

[Bilopete]

However, there is still a chance that you have gotten away with it and all will be well.

I really hope so tigermullet.....I can't afford a rebuild or a new motor at this stage. Maybe I should Terry Marine's offer up of a free motor service abd explain to them what happened after I towed their boat back to the ramp.

Apart from checking the plugs, is there anything else or any other way of testing?

I should say that after I restarted the motor I cruised it back at 10-15 knots in case it had overheated. The motor didn't skip a beat, spit smoke or play up heading back and ontop of that it was in flat fresh water, so I wasn't fighting chop, tides etc........:'(

[battleon]

Interesting.

So could it cause a problem if you had say a cat with 2 motors and 1 died then you struggle back to the ramp on the remaining one. Could you posible cook the engine from loading it up?

[tigermullet]

Sorry Bilopete, I cannot help you with diagnostics - mechanics baffle me. All I know comes from reading and experiencing a few towing problems and being aware of the dangers of over propping (actually being overpropped as well but able to recognize the problem and correct it) That knowledge came at some cost and at a time that I could have done without any further expense. The limit of my knowledge ends at being able to change water pump impellers and little things like that.

It would be good to have the motor checked over. Other than that I suppose you could go out in company with another boat and give it a try but you do run the risk of causing further damage. That is, if there is damage done already.

I would be inclined to run the motor on muffs or, preferably, in a drum at low revs and see if you can detect any overheated water out of the tell tale, spark plug missing, rough running etc. If you were concerned after that exercise it would be better to take it for a check by an expert. Seeing as you towed them back and they offered a free service they would definitely be worth approaching.

The best of luck to you. You deserve praise, not a penalty for helping out someone in trouble.

[tigermullet]

Interesting.

So could it cause a problem if you had say a cat with 2 motors and 1 died then you struggle back to the ramp on the remaining one. Could you posible cook the engine from loading it up?

Yes you could. Had it happen once with a boat set up with twin 50hp Evinrudes and 19 or 21 inch pitch props (forget which) but the boat really moved with that pair and both were spot on at 5300rpm at WOT.

One engine decided to play up in the middle of Moreton Bay. We were carrying spare low pitch props but not an island in sight to get to shallow water to change over. We limped back to port at just above idle. The motor wasn't cooked because we soon became aware that we were not going to get up on the plane even at full throttle on one engine. Cutting back to just above idle gave us the maximum displacement mode speed without loading the engine up too much. Fortunately it was dead calm and no damage was done.

In retrospect it would have been smarter to set up with lower pitch props and not run at wide open throttle ever. But we wanted speed and performance.

Having variable pitch propellers for outboard motors would be nice but that's just a dream.;D

[FNQCairns]

Pete head down to one of the auto parts places and purchase a compression tester they are usually less than $30 for the most basic type.

Real simple to use and it will in 5 minutes give you a fairly good indication of whether you can put it all this behind you and just go fishing.

Simple test is enough, take the plugs out and away + ignition off if you can do it, insert the tester and pull the engine over fast until the tester pretty much levels out say 3 pulls, then do the other hole, 2 people make it real easy but one can do it also.

It's not the be all and end all of testing compression but it is an indication and good enough that most of the industry use it.

They are nice to own and use every now and then just to see what might be going on over time.

Good luck

cheers fnq

[Bilopete]

Thanks FNQ but what is an acceptable result?


Pete head down to one of the auto parts places and purchase a compression tester they are usually less than $30 for the most basic type.

Real simple to use and it will in 5 minutes give you a fairly good indication of whether you can put it all this behind you and just go fishing.

Simple test is enough, take the plugs out and away + ignition off if you can do it, insert the tester and pull the engine over fast until the tester pretty much levels out say 3 pulls, then do the other hole, 2 people make it real easy but one can do it also.

It's not the be all and end all of testing compression but it is an indication and good enough that most of the industry use it.

They are nice to own and use every now and then just to see what might be going on over time.

Good luck

cheers fnq

[FNQCairns]

The higher the better Pete, take note of variation between cylinders, less is best, some say up to 15% is OK I personally believe closer to half that is acceptable. When you do it (if you do) throw the numbers up, someone we will be able to at least advise on your next direction. It's worth it just to get to know the engine IMO.

cheers fnq

[ozscott]

Mate - if the operator was from Terry's marine and was a mechanic he should have known better than to hit you up for a 2k tow...I wouldnt be taking my boat to that fella if he was a mechanic (I dont know if he was of course)...and if he was and it killed your engine, then you might want to consider your options...I would take it first to a reputable dealer in your brand of outboard to start with and get a written report if anything is wrong.

Cheers

[tigermullet]

Mate - if the operator was from Terry's marine and was a mechanic he should have known better than to hit you up for a 2k tow...I wouldnt be taking my boat to that fella if he was a mechanic (I dont know if he was of course)...and if he was and it killed your engine, then you might want to consider your options...I would take it first to a reputable dealer in your brand of outboard to start with and get a written report if anything is wrong.

Cheers

Thanks Ozscott. I didn't want to say that sort of thing. The thought was there but I didn't want to express it. Here's hoping that those blokes weren't mechanics because, as you say, a mechanic should have known better.

Here's hoping that Fnq's suggestion of using a pressure gauge puts things in a better light.