3 Problems that need your expertise!

[LURCHER]

we have just completed our second outing in the refurbished LONGDOG and have these three items to attend to.

1 Pronounced list to port under power yet boat is level at rest. Trimming up seems to help a little .

2 'Excessive volts' displayed on Radio GPS and smartgauges together with waning buzzer .Reducing throttle stops the problem . Showing 17.1 volts at 5000 rpm sdropping to around 14 at 4000 rpm . We run two 85amhr batteries on a three way switch . This morning 1 battery was flat and we need swith in 'both' position to start engine . The problem did not occur untill we had been running for about an hour . I assume that tis was when the flat battery had been fuly charged.


3 Max revs at WOT 5120 max allowed 5750 prop needs to be changed at present running 21p should we drop to 19'' or 20'' . Opinions gratefully recieved .

Other wise great.#

[osprey__viper]

Now then,

Item 2, poss voltage regulator faulty which may have killed the battery. Or the battery has a short and therefore knackerd. Be carefull running over volts some electronics may not like it.

Hope this helps

Martin

[robin]

John....for what it's worth.

1...Try adjusting the skeg just above the prop. I have had too many beers to get my head round which way you should/could/would adjust but like all these things a small adjustment clockwise or anti may make all the difference.

2 ....I have noooooo idea


3....Speak to Keith at Powertech (I think you know him anyhoo)...what he doesn't know about prop size/pitch etc isn't worth knowing

[codprawn]

As to the voltage problem - measure it properly using a multimeter - if it really is that high then sounds like the rectifier in the alternator gone.

[ScottyDog]

If you need to change pitch you can have your existing prop tweaked + or - 1 " for £35 (including any damage repaired) by Steel developments or Streamlined Prop repairs etc. Much cheaper than a new prop.

I have to agree about the voltage, if the regulator gives up the higher voltage will fry your batteries.

[gavin]

Had a similar problem before, with just the cranking battery in circuit connect a DIGITAL multimeter across the terminals. you should read 12v 11.8 or something similar.When you crank the opti, remember some batters deliver several hundred cranking amps, this causes a voltage drop, and with the motor running you will immediately notice the battery voltage increase , as the alternator replenisihes the battery.Running voltage will be above 12v and steadily rise to approx 14.8 volts.This is fine and normal for a 12v cell to be charged at more than 12v, if your voltage climbs above 14.8, you get alarm, warning etc.The problem you have can believe it or not be caused by resistance in battery connections , ie bad connections, or resistance (corrosion) in a battery isolator terminals.In order to deliver the charging amps the additional resistance needs to be overcome so, voltage can rise here.However I think your problem is a faulty voltage regulator, its not stopping the voltage increase as the battery gets charged up, and dissapiating it as heat, but letting the voltage climb dangerously.Regulators are often contained in the EMM module, some are watercooled etc, I cant say what the set up is in the OPTI, A rectifier is only used to change alternator a/c to battery d/c nothing to do with voltage control.

[Richard B]

Originally Posted by LURCHER

1 Pronounced list to port under power yet boat is level at rest. Trimming up seems to help a little .

Is your engine mounted centrally? Sounds like it may need to be offset to starb'd. Alternatively mount battery and stow all heavy kit to starb'd. I guess that as you've got a central helm/console then the weight of your good self you isn't compensating for prop torque either.

[Matt]

Rectifier, or regulator?

Originally Posted by codprawn

As to the voltage problem - measure it properly using a multimeter - if it really is that high then sounds like the rectifier in the alternator gone.

[LURCHER]

thanks for all replies so far , tried to replicate voltage problem today and never went above 14 volts ! So now what do we do ?

[Jeff]

Originally Posted by LURCHER

thanks for all replies so far , tried to replicate voltage problem today and never went above 14 volts ! So now what do we do ?

Hi,
Today, did you have the battery switch on "Both" as you did when you had the problem or just single ?
If so this could indicate a switch problem or wiring fault ?

Jeff

[gavin]

you may need to run engine at fast idle, to charge back up battery quickly, and repeat the problem, or run the boat, and as Jeff points out ,if the bat switch is set to both, it will take a lot longer to repeat fault, due to the added load on the alternator

[LURCHER]

The story so far ,
On a slow trip up to Northney i noticed that the top of the engine cowl and the horizontal bar of the A frame were not square ! When I got the boat out of the water Keith Whittle of Powertech and I had a good look at the engine mounting . The engine had been mounted at an angle of about 4 deg from vertical this was what was causing the list to port under power . It appears that the transom had been cut down at some point to accept an short shaft engine and the cut was not square . The current engine had just been mounted on the cut assuming it was level ! We have now repositioned the engine and lifted it 2 holes and the difference is amazing .

Still no joy with voltage . 14.2 all the way up the rev range untill 4250 then a sudden jump to 17.5 and rising with revs . Software problem?


Prop changed to 19'' s/s still not getting much more so I think I will try 17'' s/s
as I am led to believe a 19'' ss is about the same as a 21'' alloy is that correct .Does anyone have a 17'' s/s in mercury fit that I could try ?

Many thanks to all the above opinions , will get there in the end .

[codprawn]

Originally Posted by LURCHER

Still no joy with voltage . 14.2 all the way up the rev range untill 4250 then a sudden jump to 17.5 and rising with revs . Software problem?


Prop changed to 19'' s/s still not getting much more so I think I will try 17'' s/s
as I am led to believe a 19'' ss is about the same as a 21'' alloy is that correct .Does anyone have a 17'' s/s in mercury fit that I could try ?

Many thanks to all the above opinions , will get there in the end .

Have you tested the voltage rectifier??? Still sounds like your problem to me!!!

http://www.smokeriders.com/Technical..._1/part_1.html

Easy to follow with diagrams!!!

[gavin]

Rectifiers only change ac to dc nothing to do atall with stopping the voltage rise onward and upward.