Can barnacle-crusted prop cause overheating?

[GILow]

Ann, it made no sense at all. Seriously weird experience. I was poking around the boat with a boat hook thinking I must have snagged a line or something. And as soon as we cut the power the boat relaxed back to her natural position against the springers. Watching the water flow around the boat was very strange. Our prop wash in reverse has always appeared more tangential than forward, but this was even worse, pretty well perpendicular.

So when I dived on it the next week I expected to see a horrible lump of barnacle encrusted crap. But no, just a dozen little buggers, size of a twenty cent piece at most on the front face of the prop. I was not at all optimistic that I could have made the slightest difference when I climbed out of the water half an hour later, but the proof was there. Started her up, put her in reverse and out we came backwards, not exactly like a rocket, and with the usual insane prop walk. Anyway, it gave me enough control to get boat into the cradle for slipping that weekend, and now we have a lovely shiny propspeed coating and all is good again. For the record I think 18 months is about all the propspeed will mange on our boat in our current pen, so I dialled back the level of antifouling I applied a little since it looked like it could have done another 6 months easily.

Matt


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[zeehag]

always keep prop clean so you CAN move when necessary.
i have watched as friends find difficulty moving boat--oh yeah, bottom is clean---yeah but how is your prop--a ball of gop... must clean it or it wont work.

[Paul Annapolis]

This is why ship-fouling and shipworms have had a major impact on world history. Nature abhors a vacuum..... Teredo Worm | PoseidonSciences

[Paul Annapolis]

I forgot to mention another fact about these wood-eating worms According to the article cited above "In general, the sex in the wild is 1 Teredo male per 1,500 females." Ahh, the life of a shipworm. Wow--those things can really bore and tunnel!!

[GILow]

Originally Posted by Paul Annapolis

I forgot to mention another fact about these wood-eating worms According to the article cited above "In general, the sex in the wild is 1 Teredo male per 1,500 females." Ahh, the life of a shipworm. Wow--those things can really bore and tunnel!!

I'll never see a barnacle in the same way again.

[scherzoja]

This morning everything ran fine. No overheating, normal propwash.
Only difference was that this morning's temp graph was steady up to 165 degrees, where it stayed put.

This is different from yesterday, when it rose to about 140, then dropped to 120 after a few minutes, ten rose again to overhead over 30 minutes.

GILow, I'll look into the thermostat, that's for the tip

I guess I'll keep the prop cleaner from now on

[wesevans]

Did you check your through hull raw water intake?

[Lokiyawl]

Hello,

A barnacle laden prop takes a lot of extra power to drive through the water so you would be burning a lot more fuel at a given RPM, hence the engine is generating more heat than normal. Heat rejection is tied to water flow through the engine which is also RPM dependent since the faster the pump (s) turn the more coolant/seawater is moved and the more heat is removed. So you have two factors that combined could certainly lead to an overheat condition. Good luck.

James

Originally Posted by scherzoja

I'm hoping it was the 3/4" thick layer of barnacles on my propeller that caused the overheating today.

Boat hull is fine, new paint, nice and clean but prop is completely covered with barnacles.

Ran the engine today and it overheated. Elapsed time was about 40 minutes and overheated during last 15 minutes.

I also noticed that full throttle, in gear only got up to about 2200rpm (max rpm for this universal 5444 is 3000).

In gear (fwd) most of the time and noticed that the prop rotation noises were heavier-sounding and slight wobbliness.

Again, over heat was gradual and only after I pushed it up to 2000-2100 rpm for the last 15 minutes before I **** it off.

I then checked raw water strainer: clean
checked impeller: intact
Checked fresh water coolant: full

Recently cleaned out raw water system and freshwater system, so don't think there is clog there.

I swam down and cleaned off the prop, then restarted. Now, engine can exceed 3000 rpm in gear and there is way more prop wash.

I'm pretty sure the barnacles were the cause, but want to get confirmation that that hypothesis is possible. not looking forward to tearing trough the cooling system; I've got other boat things to do.

Anyway, let me know what y'all think
Thanks

[hamburking]

Not only will the barnacles kill the efficiency of the prop, but likely they won't be anything near balanced...this should cause extra vibration and noise when running. When cleared, the vibration and noise should be gone.

[Juho]

Originally Posted by wesevans

Did you check your through hull raw water intake?

I support this. If there are barnacles in the propeller, you could find them also in the raw water intake, and that could be more dangerous.

[Moontide]

Two items for you here. Sounds like your engine is running too cool. THat dip to 120 is not good (assuming that the guage is accurate). Would think faulty thermostat would the most likely cause.


Two, not getting full RPM is a big problem for diesels (and gas engines?). It indicates that the engine is overloaded and a dirty prop can cause that. Since cleaning the prop cured it I would not worry any more about that issue.

Bill

[SeaGreen]

You sure gave those barnacles one wild ride! Be careful, or word will get out.

[cabo_sailor]

Is your engine putting out any smoke? What color? Under load or not? Does it stop after a while?

Do you have a raw water sea strainer before the raw water pump? I hope so.

Has the engine exhaust elbow ever been serviced? Inspected for hole and carbon build up.

Perhaps you have a bad sender or gage. I keep one of the remote temp monitors on board. Point, pull trigger, a little laser beam targets the point being measured. Read temp off screen. You can easily check temps all over engine but I'd start with thermostat housing.

Last check for overheating would be cap used for putting anti-freeze/watèr mix in. If it is not holding pressure the boiling point will occur at lower temps.

Aren't boats fun. 😘

Rich



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