Barnacle impact on performance

A

araxton

Member
Jun 17, 2013
62
Virginia Beach
Boat Info
260 Sundancer (2001)
Engines
5.7 Mercruiser
All
Launched my 260 in April and ran great - 4600rpm/40mph. Since, I had to do the dreaded sliding door repair (managed to repair without removing helm - another story all together). Four weeks later, took the boat out and, when I opened it up, it bogged down around 3300rpm and would not get up on plane. No other signs of problem (gauges good, motor sounds fine, starts right up, etc.). I suspected fuel issue and changed filter. Didn't notice any water in old filter and planned to start going through the checkpoints in the fuel system.
Meantime, I raised the outdrive and found quite a lot of small barnacles on the props. I did not paint the bottom this year as I had painted last year and it looked to be in good shape. I painted the outdrive and replaced all zincs. I have never seen this kind of growth in such a short period of time where I keep the boat. I plan to pull it this weekend weather permitting and clean the running gear. Not sure what I will find on the bottom, but don't expect it to be much.
My question (finally) is, can this amount of growth cause such a drastic reduction of performance - consistent bogging at 3300rpm? I still suspect a fuel issue, but need to clean below the waterline anyway. Hoping, though, this might be the problem. Interested to hear others experience.
Thanks
 
With a lot of cussing and mistakes.
The critical tool was a small, very low profile 90o screwdriver (ratchet) to get into tight places. Also, I opted to cut the bottom track in half. I brought it into our tool shop at work and cut it on a water jet with a .3mm gap, then put additional screw in at the end of each piece. I was leery about this, but once done, it rolls perfectly and you can't really see the break in the track. I also opted to replace the original screws attaching the door to the track with slightly larger ones. Not as good as suggested bolts, but they went in very solid. I also laid a bead of 5200 down between the bottom of the door and the runner to take some of the burden off the screw. In all, it probably isn't as thorough as some other methods I've read (removing the helm, or drilling holes to access and bolt the door to the runner), but it works beautifully (slides with one finger) and seems very solid. Moving foreword, I plan to treat the door with a little more respect as I don't want to go through this fix again.
Good luck.
 
Yes... The barnacles will not only keep you from getting on plane, if you do it will drastically increase you fuel consumption. You need to paint every year in salt or brackish water...
 
Barnacles on the props will really reduce the efficiency of the props and their ability to move through the water.
 
araxton said:
All
Launched my 260 in April and ran great - 4600rpm/40mph. Since, I had to do the dreaded sliding door repair (managed to repair without removing helm - another story all together). Four weeks later, took the boat out and, when I opened it up, it bogged down around 3300rpm and would not get up on plane. No other signs of problem (gauges good, motor sounds fine, starts right up, etc.). I suspected fuel issue and changed filter. Didn't notice any water in old filter and planned to start going through the checkpoints in the fuel system.
Meantime, I raised the outdrive and found quite a lot of small barnacles on the props. I did not paint the bottom this year as I had painted last year and it looked to be in good shape. I painted the outdrive and replaced all zincs. I have never seen this kind of growth in such a short period of time where I keep the boat. I plan to pull it this weekend weather permitting and clean the running gear. Not sure what I will find on the bottom, but don't expect it to be much.
My question (finally) is, can this amount of growth cause such a drastic reduction of performance - consistent bogging at 3300rpm? I still suspect a fuel issue, but need to clean below the waterline anyway. Hoping, though, this might be the problem. Interested to hear others experience.
Thanks
Click to expand...

Check your trim tabs, too. When mine get barnacles, I see a noticeable difference.

Make sure that the water intake/screen on your lower unit is barnacle-free as well. It doesn't take much to restrict the flow.
 
We have a diver clean the bottom monthly during the warmer months. No choice here.
 
we had a boat in our marina with growth on it. He could not get his boat past 1500rpm and plane it.
 
Research if the type of paint on the boats bottom can be stored and relaunched?
Some paint is not affective after being stored dry.
 
Last edited:
Definetly affects it! Do a haul bottom clean, guaranteed that's the only issue.

My outdrives get growth on them like you wouldn't believe! I have to haul out every 6 months at least. In a matter of 2-3 weeks without taking the boat out there will be noticeable growth, I was out a couple weeks ago and the boat ran great. Just last weekend it wouldn't get on a plane because of growth....not even that much.

Does anyone have a better paint for using on the drives? I use "interlux trilux II" and it dosent last long at all. Also paint the props or not? (Stainless) In the past I haven't but they get growth rather quickly as well.
 
Thanks everyone for your feedback. Just had a hard time believing growth in such a short period would impact performance so dramatically. I have renewed hope that cleaning the prop and bottom this weekend will be the extent of problem.
 
araxton said:
All
Launched my 260 in April and ran great - 4600rpm/40mph. Since, I had to do the dreaded sliding door repair (managed to repair without removing helm - another story all together). Four weeks later, took the boat out and, when I opened it up, it bogged down around 3300rpm and would not get up on plane. No other signs of problem (gauges good, motor sounds fine, starts right up, etc.).
Click to expand...

Another possibility:

Does the fuel in it now contain Ethanol by chance?
If you clean up the growth and still have the problem that could be the culprit.
Ours sat unused for 4 weeks with ethanol fuel the Marina had sold without notice. We had the exact same low rpm, lack of power issue - would not plane and our hull is always spotless up here.
The fuel had separated which puts a layer of very low-octane fuel on the bottom.
Pumped the fuel out and replaced - problem solved.
 
Just finished a sea trial with a customer, 390 Carver with diesels. Boat had been sitting about a year untouched. On the way to haul out, 2200 RPMs, boat did 11 Knots, after scraping all the crap off the bottom, 2200 RPMs 18 knots.
 
All
Just power washed the bottom and running gear. Performing perfectly. Cant believe that six weeks left bottom covered with barnacles. Before cleaning, 3300rpm and wouldn't get on plane. After cleaning, jumped right on plane and ran 4600rpm. Lesson learned about bottom growth. Thanks for comments.
 
araxton said:
All
Just power washed the bottom and running gear. Performing perfectly. Cant believe that six weeks left bottom covered with barnacles. Before cleaning, 3300rpm and wouldn't get on plane. After cleaning, jumped right on plane and ran 4600rpm. Lesson learned about bottom growth. Thanks for comments.
Click to expand...

Glad it was just a cleaning and not a fuel issue. :smt038
 
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