60 HP Yamaha 2-stroke FETO (Autolube) Performance

vjmehra · 05 August 2013, 20:40

We have a 60 HP Yamaha 2-stroke FETO (autolube), circa 1990. I believe our prop is a 14" 3 blade, aluminium, recently refurbished, so virtually as good as new.

We went out yesterday in pretty flat water, seemed to be trimmed correctly and the engine sounds perfectly fine, but could only get up to 26.7 knots at about 5300 rpm. Whilst this is fairly consistent with historic performance we were hoping for a speed gain as the hull has been cleaned, the prop previously had a huge chunk missing and the engine has been serviced (our RIB is a 4.8m Humber Destroyer I believe, with the shallow V).

That 26.7 knots was SOG, but virtually at slack water, if anything the tide was with us but minimally.

Is it simply the case that we have an old engine performing as expected, or should we expect to be able to get closer to 30 knots through the water?

captnjack · 05 August 2013, 20:56

Seems a little slow. Do you have a bunch of weight aboard? Compression good?

Over here Ali props are for all practical purposes disposable since no prop shop will work on them. Good thing they are fairly cheap. Not sure what you had done to "refurbish" the one you had, but you might consider replacing it. Or at least borrow a fresh one to see if it helps.

Boatnomad · 05 August 2013, 21:01

Smallest Destroyer is 5.0m and all are deep V. As above,try a new Prop.

ncp · 05 August 2013, 21:02

Quote:

Originally Posted by captnjack

Over here Ali props are for all practical purposes disposable since no prop shop will work on them.

Not to derail the thread, but our local prop shop has no problem working on aluminum; I've had Bravo 2 that's been in on two different occasions (balance/add cup and then a fix after some rocks - I wasn't driving!)

vjmehra · 05 August 2013, 21:03

Well it originally looked like this:

Now it looks like this:

So it looks pretty good/smooth now :-)

In terms of weight, we had approx. 50l of petrol on board, 3 people, ropes, lifebuoy etc, nothing unusual.

ncp · 05 August 2013, 21:06

Quote:

Originally Posted by vjmehra

Well it originally looked like this:

Now it looks like this:

So it looks pretty good/smooth now :-)

In terms of weight, we had approx. 50l of petrol on board, 3 people, ropes, lifebuoy etc, nothing unusual.

2nd pic:
Do you always bring a propeller into the pub with you?

Looks like they did a good job on it!

vjmehra · 05 August 2013, 21:11

Hmmm, maybe I mean the Assault then?

Haha, well we were so excited at getting it back, we went out straight away to celebrate!

captnjack · 05 August 2013, 21:14

Was the boat any faster with that prop? (Historically, before it got all bent up)
The engine is 23 yrs old, and given the condition of the prop, not terribly well cared for. If it used to be faster, I'd look at compression next, maybe you aren't getting 60hp anymore.

vjmehra · 05 August 2013, 21:27

We only bought the boat 2 years ago, the prop has always been in poor condition, hence I assumed once fixed up performance would be better.

I'm no mechanic, but my guess would be that we aren't getting 60HP anymore, like you say, its a very old engine, I just wondered if there was any other possible alternative!

matt h · 05 August 2013, 21:28

I had a yam 60 with 5.3 assault. It was mental. 38 knots flat out . Im sure it overreved at 6 k. Crazy boat. But good fun

Bigmuz7 · 05 August 2013, 22:24

Jeeez .. I wouldnt go to sea with a prop like that

.. but your speed sounds ok ... especially with all those chib marks

vjmehra · 05 August 2013, 22:41

Yep, but my point is the prop has been fixed and we have no performance increase!

Pedrode · 05 August 2013, 23:35

I run an assault with a 60hp Mariner. Can just squeeze 30 knots out of her. As an aside, Im not sure I'd want to go any faster. Humber advertise this as a deep v but having compared it to others, its definitely not and it doesn't feel that stable at 30 knots in all but the flattest seas.