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Old 24-04-2016, 14:22   #1
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New motor(vetus) does not rev up to the max!

I am in France at the moment with my boat.

I have a 44ft long, 3,9m wide, 11,2m LWL, 10,2t sailing boat. Before the boat was powered by Volvo Penta 43HP with SD120 saildrive and volvo folding propeller.

....Then the Volvo broke down and it was time to consider for the new motor. I chose Vetus 4.55 (52hp) with Twindisc Technodrive SP60 saildrive with 2.15 ratio and with 18x14-3L Flexofold folding propeller.


The installation was mainly made by local boat workshop. They were not that good and they went bankrupt just before the work was done. So the seatrial was never done with them. The motor was tested only with the mechanics when the boat was out of water, so the engine was never loaded properly.


The boat was put to the water by myself and first time when I was testing the motor, I found out that the engine does not rev more than 1800rpm when the gear is on!! When the gear is neutral, the engine revs to normal 3000rpm. The boat speed in the water was around 6-6,5 KTS with just painted and clean hull...this is less than I managed to get with the old less powerful VOLVO. The hull speed should be around 8 KTS.
I was expecting the new propeller to be the problem, but after my calculations it should be ok?! I have also contacted Flexofold again and asked them to calculate again. They say it should be ok size...Then I asked from Vetus...They say it is ok size as well.

-The fuel line is 10mm when Vetus is recommending min8mm...

-The fuel has been tested with sucking straight with 10mm hose from the can to the motors electric prefeed pump. Did not made any difference.

-The Turbocharger is turning freely.

-The engine is not smoking at all.

-When the gear is on and the "gas"in full position the fuel pump linkage is in full position as well.

-The engine rotation is left...the gearbox rotation is left as well...The propeller should be left too.

-Now I tested in the marina with the boat tied up...When reversing max, the engine revs up to 2100rpm. That is more than the 1800rpm forward.




I am running out of ideas now.... The ordered propeller was 18x14-3L ....But maybe Flexofold delivered wrong propeller and the mechanic installed it without checking of it??


Please give me some ideas what I could check next?? This is very frustrating after I purchased completely new powerline to avoid problems and now I cannot use the boat because of this mystery with the motor/propulsion system...
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Old 24-04-2016, 14:38   #2
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Re: New motor(vetus) does not rev up to the max!

My first thought would be the propeller. It could be as you question, Flexofold shipped the wrong prop but even if they did ship the prop they calculated, calculations are not always correct and often to get the correct prop you have to do some trial and error.

My second thought would also be fuel. Have you checked the filters for air leaks or water in the filters? If you open the top of the filter housing is there any air inside?
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Old 24-04-2016, 15:51   #3
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Re: New motor(vetus) does not rev up to the max!

Revving to 3000 rpm max in neutral sounds low, too. Have you checked the throttle operation is reaching it's maximum limit?
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Old 24-04-2016, 18:01   #4
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Re: New motor(vetus) does not rev up to the max!

I didn't even know Twin Disc made a sail drive...

Don't know if you have an owners and installation manual, but there's one here:

http://www.timray.nl/afbeeldingen/ke...stallation.pdf

Since the engine makes its rated speed in neutral, it makes sense to suspect something between the engine and the prop, if not the prop itself.

The installation manual shows that the proper way to install the system is to glass the bed in, install the drive/transmission, and then mate the engine to the transmission. Usually this is pretty straightforward and foolproof, and I have no experience with this but there may be something that can be and is misaligned or binding between the engine and the input shaft of the transmission, especially if the installers are inexperienced or careless.

It makes sense to start with the simplest things first, though, so in addition to the suggestions above, does the gear have oil of the right kind and amount? ATF is a lot thinner than 90 weight gear oil...
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Old 24-04-2016, 18:02   #5
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Re: New motor(vetus) does not rev up to the max!

Fuel blockage. Look for a kink in one of the feeds on the motor. Check all fuel filters for gunk. Your boat has been sitting around for a while maybe with partially filled tanks. Bleed the fuel pump at the motor.

Then check to see that you can rotate the shaft by hand no engine and out of gear, maybe a corroded shaft. Check that stuffing box doesn't get hot when operating.

Take the propellor off in the water and operate the motor. If it runs to max then it's the prop.
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Old 24-04-2016, 19:01   #6
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Re: New motor(vetus) does not rev up to the max!

I think you are over-propped.

The prop calculator I used suggests a 17 x 12 propellor for your application. (This is for a fixed prop).
https://www.vicprop.com/displacement...tion=calculate
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Old 25-04-2016, 02:06   #7
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Re: New motor(vetus) does not rev up to the max!

Thank you for ideas this far...

The fuel supply was tested also straight from the can with short hose and connected straight to the engines own electric feed pump. The fuel looks good in the can and also in the racor filter glass bowl. No water detected either. The fuel tanks has been topped up.

The electric pump should be able to deaerate the system by itself. The engine sounds also very healthy and not like it would pass any cycles as if there would be air.


The corrosion problem is not likely since the whole powerline is new and this problem was there when the boat was tested in the water first time.
There is no stuffing box, since this is saildrive.

The gearbox/saildrive is filled with correct oil.

The motor was installed in the order as follows:
First glassed the motor/drive bed to the hull...Then installed the saildrive to the bed and then the motor was slided to the saildrive and bolted to the bed. The group was really bunch of amateurs, but possibility for bad alignment or that causing the running problem is fairly small...



My first suspicion is the propeller...But flexofold and also vetus are saying the size 18x14 is good.... And at least should not infect to the engine speed dropping 1200rpm from the max!

The 3000 is the VETUS 4.55 max rpm by the manual. It should not turn more than that.






I am afraid the boat will be lifted up today and check if the propeller is the ordered size or not....
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Old 25-04-2016, 05:34   #8
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Re: New motor(vetus) does not rev up to the max!

Quote:
Originally Posted by Jani-SRI View Post

I am afraid the boat will be lifted up today and check if the propeller is the ordered size or not....
Seems like the best plan.

Could also be something like being unlucky enough to pick up a small line immediately on your first run (stranger things have happened), or having the wrong prop spacer installed.

Just out of curiosity, what was the prop size with the Volvo?
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Old 25-04-2016, 05:56   #9
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Re: New motor(vetus) does not rev up to the max!

Quote:
Originally Posted by Jani-SRI View Post
Thank you for ideas this far...

The fuel supply was tested also straight from the can with short hose and connected straight to the engines own electric feed pump. The fuel looks good in the can and also in the racor filter glass bowl. No water detected either. The fuel tanks has been topped up.

The electric pump should be able to deaerate the system by itself. The engine sounds also very healthy and not like it would pass any cycles as if there would be air.
This is how I test possible fuel problems and has helped me solve similar issues in the past. Since I am not familiar with the Vetus I do have one question. The diesels I am familiar with do not have an electric fuel pump for operation. They have had mechanical pumps for bleeding air from the lines for example when changing filters and I have seen electric pumps for the same purpose but not to pump fuel to the engine for normal operation.

So is this electric pump for priming or bleeding or for normal running? If not for normal operation I might consider doing the same test with a fuel can but bypassing the electric pump just in case there is some kind of leak or restriction in that pump causing the problem.

It is obvious from your questions and tests so far that you understand that the your problem with low revs could be from limited fuel since the engine under power uses much more fuel than revving in neutral or from a propeller problem.

Again, even though all the professionals say this is the correct prop, if you have eliminated the fuel problem then I would say 99% it must be the prop. Years ago I purchased a 19' power boat brand new from the factory dealership. The boat would not rev to full rpm, top speed was limited and it took too long time to pull a skier out of the water. I changed to a prop with slightly lower pitch and all was perfect. So in that case even the original manufacturer put the wrong prop on a boat with the standard engine from the factory new.

I have read articles even from propeller manufacturers that suggest calculations can get you close but the final determination on what size is really determined by testing the prop on your boat.
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Old 25-04-2016, 05:57   #10
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Re: New motor(vetus) does not rev up to the max!

Too windy today...so not lifting the boat out of the water today... Maybe tomorrow is better weather??

The old volvo prop I do not remember....the motor was 2003t 43hp with sd 120 saildrive. The propeller was Volvo's own foldable with those "bumerang" -shaped blades.



I have de aerated today again from the fo filter and as the manual says, the engine is self deaerating. That is because of the electric feed pump.




I have asked from Flexofold before about the possibilities to install the propeller somehow wrong, but they said it should not be easily done and if it would be wrong, then I would hear it when running the engine with the gear engaged.
When I expressed my concern about the possible wrong size of propeller, they said that the prop is good size, but might limit the top rpm just below the 3000max, but still enabling the boat to reach the hull speed easily.

Before I read from somewhere that the 1" in prop size is around 100rpm in engine speed. So maybe the blade "lift" is too strong?? But how badly it has to be wrong to cause 1000rpm difference in the engine speed??


this is the feeling with the current set up at the moment:
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Old 25-04-2016, 06:26   #11
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Re: New motor(vetus) does not rev up to the max!

Were you going straight into the wind? How much wind?

If so... try a run with the wind.

Cheapest and easiest test I can think of.
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Old 25-04-2016, 06:54   #12
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Re: New motor(vetus) does not rev up to the max!

Quote:
Originally Posted by Jani-SRI View Post
Before I read from somewhere that the 1" in prop size is around 100rpm in engine speed. So maybe the blade "lift" is too strong?? But how badly it has to be wrong to cause 1000rpm difference in the engine speed??


this is the feeling with the current set up at the moment:
When I have changed props in the past I kept the same size, that is the diameter or the length of the prop blades and changed the pitch which is the angle of the prop blades or how much bite they take from the water. Changing the pitch by 1" if I recall, has a much bigger change than 100 rpm. On one speed boat I saw a very big change going from a straight prop to a cupped prop. Don't know if this term translates so to clarify, a cupped prop has a small bend along the back edge of the prop so it is slightly concave.

I am more and more suspecting the prop.

By the way, I am planning a Flexofold prop for my boat and have spoken with their US distributor. They were very clear that they would help choose the correct prop for my boat but also said it is very common to have to make a change and their policy was to swap the blades one time at no charge if the original prop wasn't just right.
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Old 25-04-2016, 07:10   #13
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Re: New motor(vetus) does not rev up to the max!

I've no experience whatever with your boat, engine, saildrive or propeller so this is based only on a quick look at Flexofold's online installation manual - which isn't exactly comprehensive.

Only one thing springs to mind that hasn't already been mentioned and that's the spacer washer, item 3 in the exploded drawing.
Not supplied by Flexofold apparently so presumably different for each saildrive manufacturer & model.

If it were slightly too thick it might be possible for that spacer not to bind in either gear out of water - or even in water in reverse gear - and yet still bind in forward gear in the water when thrust forces the propeller hub forwards.

I'd expect some measurable backlash at the propeller shaft would be essential to avoid rapid wear of the saildrive's lower gears. The saildrive manual should provide a measurement procedure.

If the spacer were taking up that designed backlash it would be best to correct it quickly.

ps. I'd now give the work to the best, most well-respected and professional company I could find given your experience with the now-bankrupt installer.
Too easy for all the suppliers to disown warranty on engine, drive & propeller by claiming non-compliant installation.
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Old 25-04-2016, 07:14   #14
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Re: New motor(vetus) does not rev up to the max!

Why don't you check prop calculation at our website, it' free of charge of course !

You just need a few informations about boat and engine + gearbox:
Calculate your propeller



Quote:
Originally Posted by Jani-SRI View Post
I am in France at the moment with my boat.

I have a 44ft long, 3,9m wide, 11,2m LWL, 10,2t sailing boat. Before the boat was powered by Volvo Penta 43HP with SD120 saildrive and volvo folding propeller.

....Then the Volvo broke down and it was time to consider for the new motor. I chose Vetus 4.55 (52hp) with Twindisc Technodrive SP60 saildrive with 2.15 ratio and with 18x14-3L Flexofold folding propeller.


The installation was mainly made by local boat workshop. They were not that good and they went bankrupt just before the work was done. So the seatrial was never done with them. The motor was tested only with the mechanics when the boat was out of water, so the engine was never loaded properly.


The boat was put to the water by myself and first time when I was testing the motor, I found out that the engine does not rev more than 1800rpm when the gear is on!! When the gear is neutral, the engine revs to normal 3000rpm. The boat speed in the water was around 6-6,5 KTS with just painted and clean hull...this is less than I managed to get with the old less powerful VOLVO. The hull speed should be around 8 KTS.
I was expecting the new propeller to be the problem, but after my calculations it should be ok?! I have also contacted Flexofold again and asked them to calculate again. They say it should be ok size...Then I asked from Vetus...They say it is ok size as well.

-The fuel line is 10mm when Vetus is recommending min8mm...

-The fuel has been tested with sucking straight with 10mm hose from the can to the motors electric prefeed pump. Did not made any difference.

-The Turbocharger is turning freely.

-The engine is not smoking at all.

-When the gear is on and the "gas"in full position the fuel pump linkage is in full position as well.

-The engine rotation is left...the gearbox rotation is left as well...The propeller should be left too.

-Now I tested in the marina with the boat tied up...When reversing max, the engine revs up to 2100rpm. That is more than the 1800rpm forward.




I am running out of ideas now.... The ordered propeller was 18x14-3L ....But maybe Flexofold delivered wrong propeller and the mechanic installed it without checking of it??


Please give me some ideas what I could check next?? This is very frustrating after I purchased completely new powerline to avoid problems and now I cannot use the boat because of this mystery with the motor/propulsion system...
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Old 25-04-2016, 07:27   #15
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Re: New motor(vetus) does not rev up to the max!

I've been reading instruction manual over and over again to find something new....

oops...I got the max rpm wrong. The 3000rpm is the rpm for max power, but the engine is revving a bit more after that and especially without load. According the UK manual the max rpm without load is 3350rpm, according the FR manual it is 3250. Mine is revving to 3000rpm when the gear is in neutral... So if the engine is losing 10% without load....then it can lose even more with the load....?

So...the adjustment for fuel stop can be wrong......OR the rpm is not calibrated properly? I do not have a other tachometer except the one in VETUS panel.


I asked from the "vetus" shop, but they are not so helpful...
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