Prop hub slipping or worse?

[TerryW]

I am researching a nasty little fault that just developed out of the complete blue today. Just going out on a flat calm sea to tease the cod fish. Came out of the lock at hull speed no problem. Pointed the nose towards the third star on the right (sorry for the Cap'n Kirk reference) and squirted the throttle to 3200 as per the usual 'get on the plane' procedure. She climbs to 3200 revs under load , starts to point the nose up and suddenly the "clutch slips" like an old Austin car. NB I still have good drive below 3000 revs . I tried the same procedure a few more times just to make sure that I wasn't doing anything stupid.

The instant diagnosis is "bu99er I must have hit something and spun the propeller hub". So, I limped home to port and docked up and ripped the prop off at the dock. No 'dinks' on the prop, no ropes hanging therefrom. Nothing.

I took the prop home and put it on my spare outdrive, locked the drive shaft and tried to spin the prop. No go. It is solid as a rock with my 160lbs trying to wrench it round. OK, so I can't produce a whole lot of power to spin it, so it might not be a very thorough test.

I'll pop back to the boat with number one spare prop in a day or two and see if I get proper drive. But, in the mean time I am wondering what else might cause a "slip" issue like that. There is no burning rubber smell (as per a shot coupler) and I can't really think of anything in the system that might simulate a burn-out car clutch.

Any ideas?



PS The prop was a 2015 Solas 4 blade aluminium prop. It is the type where the hub is not replaceable (I checked with the shop). Shame the shop is in Ireland or I'd take it in for them to test properly.

[builderdude]

I'd say put on your spare prop and if it happens again your couplers on the way out, If not it was likely the prop hub.

[Nauti_Mike]

I agree with Dave, it's most likely the prop hub. I had one do the same and it would hold load of my 5000 lbs boat up to 2000 rpm before slipping. the prop had no damage just the old rubber broke free. You can mark the inner and outer hub with a set punch and when the issue happens see if the two marks are no longer aligned.

[RobMick]

I had same issue with a 2015/2016 Solas Amita 4-blade aluminum prop. Idle speed through channel, out to open water, slowly added power and as I did, engine rpm's jumped. Having NEVER spun a hub before, I panicked originally but settled down and thought that was the problem. I replaced the prop with my spare while there in the open water...10 mins and one of those things that in retrospect, I am glad I did for the experience. Anyway, like you, I examined the prop and no damage from an underwater object strike....I think the hub just let go....prop was on its second full season with steady use. Lower unit Always stored in down position with lower leg in water, prop below waterline. I have not had a proplem since replacing with same prop... I did all the necessary stuff as well such as applying some anti-siege lube prior to mounting prop.....maybe it was just a "that's the lifecycle" of that prop....I keep in mind, that those props are rather inexpensive about $100. If I had to replace on every year, so be it...I will have a better history this season as the current prop will be in its second season of use in fresh water...I love the prop though for my 185.....Solas Amita 4 14.25x19

[TerryW]

good comments guys. Yep, the prop wasn't expensive. It cost £160 here in the U.K. Great idea about pin-marking the prop. I like that one. I'll get back to the boat shortly, put the spare on and post the results. I love my old Solas prop 14.25 x 19. It gave a 10% fuel saving and a 3 knot faster cruise for the same rpm. Not sure about buying another one if they only last 2 years though.

[Pcpete]

I believe you have a failed prop hub. The indicators you described are bang on. I had that problem for a couple of years on my last boat. Mercruiser Alpha drives, rubber prop hubs. The core problem, it was explained to me, was the glue was changed and degraded in about a year, especially if the boat was stored in the water. I changed to the glass reinforced plastic type and that was the end of the problem. I never had an issue with the plastic failing when it shouldn’t, like the rubber hubs, or not failing when it should.

[Centerline2]

I agree with Daves comment
its unlikely both props have bad hubs, so install the spare prop. if the spare prop works well under load, the hub on #1 prop is bad, but if you get the same symptoms with the spare as you did with prop #1, you are probably going to find you have a drive coupler/damper issue, as these have the same symptoms as a spun prop hub.
if it is the drive coupler, and you continue to keep the power on and let it slip for a minute or two, you should begin to smell rubber getting hot... if you do, its most definitely the drive coupler and not the hub.

we can only hope its a failed hub, but if it is the drive coupler, it can usually be changed in 3-4 hours... unless there is a problem removing it from the shaft.

[Chief_Alen]

For the future if some one has this problem, scratch a line thru the hub on two sides if the line doesn't match up after a run and the slipping you know it's the prob hub.

[TerryW]

Just getting back. The spare prop worked fine so it is the Solas prop being a pain. Shame. NIce prop but only lasted less than 100 hours. Not sure what to buy next. I can live with the 15 x 17 for now but WOT is in excess of 5000 rpm so a new prop would be nice. Plus, I got better economy from a 4 blade.
Thanks for all the help guys.
Terry

[Nauti_Mike]

Glad it was just the prop. Being an Alpha you can buy a new prop for the cost of replacing the hub. The last time I had a prop rehubbed it cost $150 US but I hav3 a Bravo II and a alumium prop is $300 - $500

[Ruffryder]

one more reason, why I use a derlin sleeve prop / flo torque hub.

[Pcpete]

Shop online carefully. I was buying counter rotating four blades without the inserts for about $110 each USD. I never needed in kit and it took me some time to figure that out.

[Centerline2]

Just getting back. The spare prop worked fine so it is the Solas prop being a pain. Shame. NIce prop but only lasted less than 100 hours. Not sure what to buy next. I can live with the 15 x 17 for now but WOT is in excess of 5000 rpm so a new prop would be nice. Plus, I got better economy from a 4 blade.
Thanks for all the help guys.
Terry

I would get a second opinion on the NON replaceable hub... unless its for a small outboard, that would be a rare prop that has a rubber hub but isnt replaceable... especially a solas prop that is less than 20years old..

[TerryW]

I am still hunting for a repair solution and will post back if I can find anything. There may be a little prop shop tucked away in some village near the sea.

[Centerline2]

I am still hunting for a repair solution and will post back if I can find anything. There may be a little prop shop tucked away in some village near the sea.

set it on the bench and with a block of wood on the spline part, try to drive it out the back of the prop.... if its spun, it shouldnt take much pressure. solas props are made so that the consumer can change the hub themselves, but sometimes the rubber can become stuck and needs a bit of persuasion with a hammer. after the splines are out, a small scraper or screwdriver and wd-40 can be used to get any remaining rubber out of the prop.. the wd 40 is so it lubricates the rubber so its easier for the scraper to be worked thru and loosen the remaining rubber

[RobMick]

To my knowledge Solas makes 2 models of props, Amita which is the pressed hub, and Titan which has the replaceable hub....I don't know what the warranty is either. I would think that the hub in the Amita cannot be replaced....hence the other model of prop...