Welcome, Guest
Username: Password: Remember me
  • Page:
  • 1

TOPIC: Boat Slower At Same RPMs?

Boat Slower At Same RPMs? 13 Jul 2017 15:12 #1

  • mguelker53
  • mguelker53's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 30
  • Thank you received: 3
We noticed on our last time out thatwe were moving slower at the same RPMs. We have always been a 7 knot boat at 1800 RPMs. Taking into consideration the prevailing currents with or against us, if there is little or no current, we go 7 knots at 1800 RPMs.

So, what could be the reason why we suddenly have to apply 2200 RPMs to still attain 7 knots?

Please Log in or Create an account to join the conversation.

Boat Slower At Same RPMs? 13 Jul 2017 15:40 #2

  • mmichellich
  • mmichellich's Avatar
  • Offline
  • Platinum Member
  • Platinum Member
  • Posts: 7217
  • Thank you received: 379
Is there new bottom growth? Do you see an engine smoking now that was not before? Are you towing a crab pot or something?

Please Log in or Create an account to join the conversation.

Started boating 1965
Bayliners owned: 26 Victoria, 28 Bounty, 32, 38, and 47 since 1996

Boat Slower At Same RPMs? 14 Jul 2017 15:58 #3

  • mister larry
  • mister larry's Avatar
  • Offline
  • New Member
  • New Member
  • Posts: 56
  • Thank you received: 26
Interesting question: why is it taking about 20% more power to maintain your cruising speed?

Without getting into great, mechanical questions, the bottom growth dilemma is quite common. In both salt and fresh water the boat can pick up growth below the water line. Then there is a trim tab question. Could someone have mistakenly pushed the button and moved the tabs into a more downward position? Next in line (without hauling the boat) is an engine analysis. Are all cylinders operating? Is something blocking the air intake into the engine compartment?

Finally, and no one hopes, that you have an underwater running gear issue.

Please Log in or Create an account to join the conversation.

Boat Slower At Same RPMs? 14 Jul 2017 16:11 #4

  • smitty477
  • smitty477's Avatar
  • Offline
  • Platinum Member
  • Platinum Member
  • Posts: 5686
  • Thank you received: 954
mmichellich has the answer - it is either growth on the hull or growth on the running gear and likely both.

It cannot be the engine(s) if the rpm on the shafts are increased to 2200 to attain the same speed.

Please Log in or Create an account to join the conversation.

Northport NY

Boat Slower At Same RPMs? 14 Jul 2017 22:06 #5

  • floatyerboat
  • floatyerboat's Avatar
  • Away
  • Elite Member
  • Elite Member
  • Posts: 700
  • Thank you received: 91
I was also thinking trim tabs. They may be stuck or in the down position and the system isn't working at all. If you cant see thru the water you can take a broomstick or something to see if they are working properly.
Gas? Diesels?
If gas I wanted to add I just installed electronic ignition and with problems very similar to yours, they've vanished and I have speed I've never had in three years.
It wouldn't hurt to check your transmission fluid also.

Please Log in or Create an account to join the conversation.

Dan
Frostbite Falls, Minnesota
Claudia V. III
1988 - 3218
Gas Drives
Last Edit: by floatyerboat.

Boat Slower At Same RPMs? 14 Jul 2017 22:59 #6

  • yachtman
  • yachtman's Avatar
  • Offline
  • Platinum Member
  • Platinum Member
  • Posts: 3732
  • Thank you received: 293
When I bought my bayliner 32ft conquest it would only do about 5- 8 mph tops. I pulled it out cleaned the bottom and immediately got 32 mph.






Cleaned up and all was good.

This message has attachments images.
Please log in or register to see it.

The following user(s) said Thank You: mguelker53

Please Log in or Create an account to join the conversation.

1989 Avanti 3450 Sunbridge twin 454's

1979 Bayliner Conquest 3150 hull#23

1979 Bayliner Conquest 3150 hardtop hull#24
Twin chevy 350's

Boat Slower At Same RPMs? 17 Jul 2017 05:15 #7

  • Pat Careen
  • Pat Careen's Avatar
  • Offline
  • New Member
  • New Member
  • Posts: 46
  • Thank you received: 10
Are both of your transmissions engaging? Maybe shifter cable issue? 2200 rpm is about right for one engine at 7kts.

Please Log in or Create an account to join the conversation.

1988 3218 Figgy Duff
135 Hinos

Boat Slower At Same RPMs? 22 Aug 2017 19:57 #8

  • mguelker53
  • mguelker53's Avatar Topic Author
  • Offline
  • New Member
  • New Member
  • Posts: 30
  • Thank you received: 3
Thank you all who sent replies. All were useful responses and I will keep those things in mind in the future. However, the solution turned out to be New bottom paint. We had serious growth on the ottom and we're overdue for new paint. Also had a lot of mussel growth that hadn't been caught by our divers. Thanks all.
The following user(s) said Thank You: robster_in_edmonds

Please Log in or Create an account to join the conversation.

Boat Slower At Same RPMs? 23 Aug 2017 18:10 #9

  • Centerline2
  • Centerline2's Avatar
  • Offline
  • Junior Member
  • Junior Member
  • Posts: 97
  • Thank you received: 15

mguelker53 wrote: had a lot of mussel growth that hadn't been caught by our divers. Thanks all.


paying someone to do something they arent doing?... I would be finding a different company to do the BWL maintenance....

Please Log in or Create an account to join the conversation.

1989 Bayliner 2556, 5.7 OMC Cobra

Boat Slower At Same RPMs? 23 Aug 2017 23:53 #10

  • jas0381
  • jas0381's Avatar
  • Offline
  • Premium Member
  • Premium Member
  • 8054510517
  • Posts: 428
  • Thank you received: 27
I suspect you were being kind about the divers missing mussels.?!

Please Log in or Create an account to join the conversation.

Joe
2001 5288
Lucky Liner ll
  • Page:
  • 1
Moderators: higgins_jrJim Gandee
Time to create page: 0.097 seconds
Powered by Kunena Forum