Hit a log

[William Walter]

Not a good day today as I hit a submerged log in the middle of the ocean. I knew right away that both props were hit and damage had accured .was able to limp home at idle.hopefully tomorrow boat gets hauled and I can see the damage. I’m thinking at this point just props but could be worse. I’m sure insurance will be involved so I want make sure I cover all my bases.I’m thinking cutlass bearings,struts,shaft seals,shaft checked.is there any way to check transmission for damage.At idle for 4 hours coming home no leaks.only leak was from impact but just a few drops through shaft seals.Engines seem fine along with transmission.normal pressures and temperatures.Bill

Topic

[William Walter]

Bearings

Thanks Jimmy for the info. I just got back from the boat and after cleaning up the back end of the bearing better I remeasured and indeed Tiara was right at 3 inches od. I agree with you about it not being the problem but I think while everything is out and I have no idea when they were done last it was best to do them. I took my props to my prop guy and learned a couple of things.One was that they weren’t a matched set with the stbd having been replaced at one point.It had a thinner hub that is almost 1 inch longer than the other. I always wondered why there was a difference how they were positioned on the shafts.He says not to mess with them now and see how things pan out after all the work is done. I’m also fixing one trim tab which I narrowed down to the wire between the switch and the motor.Not sure if that’s a factor or not.It will be interesting to see how things pan out in the spring .

[JimmyK]

You can measure the OD of the bearing without removing it.  Might have to remove the prop.

A bearing puller is helpful but I cut mine out w/a sawzall (carefully).  Not hard to do.  Used a couple lengths of threaded rod and an assortment of washers to install the new one.  Kept the new bearing on ice and heated the strut mildly and evenly with a torch before install.  Again, not hard.  On mine there were 2 set screws on each side of the strut (hard to see with years of paint and other stuff covering them).  Tiara gave me accurate info on the size of the bearing.  They have excellent records…really an amazing company with the way they are quick and thorough to support 20+ year old products…not saying they’ve never been wrong but I would absolutely trust the info they give…just try to verify it I guess.

I doubt the bearings are contributing to your issue but agree with your thought process that if they are paying to remove the shafts you may as well replace the bearings and shaft seals while the shafts are out.

[William Walter]

Cutlass bearing

Thanks all for the info. I was not planning to remove and install bearings as I just don’t have the tools for the job.Hopefully the yard will pull the shafts soon and we can confirm the bearing size. I was planning to purchase bearings though. I also discovered that my port trim tab is stuck in the position I normally use for cruise .On the last test run I couldn’t get it up when I went to wot. I’m not sure if this is affecting my burns at 2100 as the boat feels pretty trimmed at that speed but above that it’s definitely a drag on the operation.Seems I have a bad relay on that side.

[Rob Schepis]

Bill,

Safest best is always to pull what you have and go from there.  A call to the builder is always risky – things may not have followed suit at the time of the build, and anything could have changed in the years that followed…

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William Walter

[Tony Athens]

Gene,

 

Just an FYI. 3 inch ID struts are not odd for boat like this. 2 inch shaft bearings do come in 3 inch OD but the brass shell is not thicker — still 1/8″ wall thickness like yours– but the rubber thickness in now 3/8 inch thickness vs 3/16 inch on the 2 5/8 inch OD cutlass. IMO, we prefer in many cases . With the builder using a larger ID strut, it adds a lot of flexibility to the overall build.

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William Walter

[Gene Fuller]

Cutless bearings come in a great many sizes, typically identified by a name. I would be very surprised if anyone used a 3 inch outer diameter for a 2 inch shaft. A lot of expensive bronze for no benefit. I would be even more surprised if someone machined the OD, since there are so many sizes available.

 

I don’t have a Tiara, but my boat has a 2 inch shaft. The Cutless OD is 2.5 inches. At the same time the stern tube OD for fitting the PSS seal is 3 inches.

 

Someone at Tiara may have mangled the numbers.

 

Gene

[William Walter]

Cutlass bearing

My insurance company via a surveyor has decided to pull my shafts because they are slightly over limits. I don’t think it will solve the  issue but I don’t mind since my pss boots need doing and two motor mounts need changing. I also plan to change cutlass bearings so everything will be new or reconditioned in the drive chain. I was going to order mounts,pss,an cutlass bearings but got a little confused when it came to the bearings. I asked tiara the size for the pss and cutlass bearing.The pss match what I have but the 2 by 3 by 8 cutlass bearings seem a little big in the 3 inch part as when I measured mine the outside diameter seemed to be around 2 and 3 quarter. I had heard somewhere that the outside is machined but wasn’t sure.Having never done cutlass bearings I was wondering how the sizing of the new ones worked.

[William Walter]

Motor mounts

Enclosed are two pictures of my mounts. The right rear mount is compressed and the others are like the other picture.In a perfect world I guess you would replace them all but would it be ok to just replace the compressed one.Is the job relatively easy to do one at a time. I guess I would wait till I get put back in in spring to align.

[William Walter]

Thanks Jimmy props were done 3 years ago so I had a pretty good baseline of performance of both engines.The numbers aren’t terrible after the second reconditioning but I know something is not right on the stbd side.my goal was to achieve a 13.6 fuel flow at 2200 rpm which is what Tony recommends.Frustrating part is that I achieved that on the port engine with the changes I made but the stbd side didn’t make it.Not sure at this point if I want to trick the stbd prop which may be masking another problem..

[JimmyK]

you mentioned vibration after the first prop work. How is the vibration now?

Obviously seems that something is off but can’t be too bad based on your numbers. When was the last time you had the props scanned before hitting the log? Perhaps the props were tuned so that loading between engines was similar rather than tuned so that they measured exactly the same on the prop scan? And to get back to where you were before you might have to get the props a bit mismatched? As you’ve shown, even slight tweaks to the props will have an effect on fuel burn. just thinking out loud here.

with that said, let the insurance co’s mechanic take his time…he may tell you that you need a new pair of qsc’s 🙂

[William Walter]

Fuel burns

Clark before hitting the log fuel burn on the stbd was always historically less than the port.maybe 4 tenths of a gallon.when props were reconditioned I took some pitch out and was expecting results l got on port engine for both.port engine is exactly what I was hoping for performance wise. Props were sent out twice because I had vibration and even higher fuel burn on stbd.After second reconditioning I went from a 2 gallon higher burn on stbd to about 1 gallon which I have now.They assure me they are 100 matching.who knows.

[Clark Leighs]

I would say a difference in fuel burn between P & S is not abnormal compared to many installations. Maybe the difference is a bit more in your case. However without knowing what they used to run at it’s a guess.
Did you track the fuel burns?

However, a prop difference from the repairs could be part of it. A still existing misalignment could account for some.
If the engine mount is compressed then something is out of whack and the engine may not be supported properly as you suspect. All the mounts should be checked as that one may not be the problem.
Maybe one on the other side has been damaged forcing the engine to lean.

[William Walter]

Sea trial

Surveyor who is assigned to my case wanted Cummins mechanic to look over engines.Two things he found was stbd rear right motor mount compressed and when he cracked the injectors some blackish fuel.we changed the racor and on engine filter with no change in stbd engine performance.When he mentioned the compressed mount which would make sense after hitting a log it got me thinking that maybe even though my alignment was on at the dock maybe when the torque of the engine comes into play it wasn’t . I ran the boat at 1000,1500,2000,and2200.as you can see the fuel flow is better at the lower rpms but gets progressively worse on stbd engine as power increases.Not sure if that’s possible or if anyone has seen that.

[William Walter]

Thanks Rob. Good info. I had been calling the adjuster but decided to also Email so I had a record of my communication.I’ve been also doing that with the yard which has already saved me In one situation where they said they never told me something but I had email to back up what I was told.Bill

[Rob Schepis]

Good info from Mike there. Bill, be sure to keep the insurance adjuster fully informed each step of the way. They do not like surprises, especially on claims that in their mind could/should be “closed” claims. Furthermore, the policy language gives them the right to inspect the property as often as they reasonably require so if you do something without notifying them they can deny.

[William Walter]

Thanks for info Mike . I did open a claim and thought it would end with the props. We redid the props which made a difference but we’re not there yet. Going to have the shaft rechecked also.Everything seems to spin nicely but something is different from before I hit the log.Bill

[Mike Salsa]

I’ve hit a log too

Just thought I’d throw this out there. My 50ft Azimut with Cummins QSB 5.9’s and V-Drives hit a log a few years ago. Initially they only replaced the props. When I joined the boat a little over a year after the incident, I mentioned to the owner that there was some vibration that we should have looked into. We did a vibration analysis and found big problems. When we hauled the boat we found one prop needed to be balanced, the other reconditioned and balanced, and BOTH shafts bent. Upon re-installation, the same company that did the vibration analysis did an optical alignment. They found one strut bent and out of alignment. Considering how much was wrong with the running gear, you’d think the vibration was terrible but it really wasn’t. It was a nominal vibration that the lifelong boater owner didn’t even notice.

Fast forward a month after all that work was done. One of my transmissions started slipping gear and ultimately needed to be replaced. Fast forward another 6 months and my PTO pump on the other transmission stopped working. We found that transmission in need of replacement also.

In my opinion, if I’m ever in a high speed collision with the running gear, I’ll immediately open an insurance claim and go through the whole running gear with a fine tooth comb… from the props all the way till the transmission. This has been an extremely costly incident that we couldn’t make a claim on because of how much time had passed.

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Rob Schepis

[William Walter]

Props

So we sent props back to prop shop again and I sea trialed boat .my results are better but not what I hoping for. I went from a 2 gallon an hour difference between the engines to about 1 gallon.The port is pretty close to what I wanted at 12.8 gals an hour at 2100 but the stbd is at 13.8 at 2100.at least I can get to full power now on stbd but load is 96 stbd and 89 port.Prop report looks fine unlike first report I received. Obviously it was a good move to get the props dialed in better as I saw definite improvement.I’m a little perplexed where to go next .The stbd side took the brunt of the log hit.

[Steve Lewis]

I calculate slippage by taking my actual vessel speed at a particular RPM and divide by the theoretical speed.

At 2140rpm I am getting 22mph actual. I have 23×26 props and 1.77 ratio. Theoretically speed should be 29.76mph. Do the maths and I get .739 on the efficiency side. 1-.739=.26 so Slip is 26%

I attached a spreadsheet with the formula in it for fun. We have the same engines so I figured you might find it relevant.

I am going to take 1 more inch out at winter layup to get things dialed in a bit more from a fuel burn perspective. I am interested in how the slip will change. With 1 inch taken out after the sea trial I noticed an improvement in slip.

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William Walter

[Rob Schepis]

I don’t think a delta of less than 20 thou is gonna make much of a difference, either way you’re in the “medium” cup ballpark.

We have had some prior threads on slippage, search “Prop Slippage”

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William Walter

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