I've lost some knots.

Sticky Fingers

Sticky Fingers

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Not those you tie into ropes / lines / whatever. The speed ones. I had loads a few months ago now I'm missing 8 of them, that's 25%.
  • Speed through water on commisisoning in April was 32kts at about 3400 rpm
  • 8 weeks later, max speed was down to 30 kts. Burning 3.8 litres/mile. Tanks full, 2 up.
  • Now after about 4 months I can only get 24kts at about 3000, and fuel burn up at 4.2 litres / mile. Tanks half full, 2 up, so about 250kg lighter.
All at WOT, minimal wind and waves, and so this is not a happy story. Not sure what effect of burning more fuel at lower RPM to go more slowly might have on engine temperatures etc, so yesterday I throttled back to 18kts rather than running any faster.

Must be fouling I assume, but I'm surprised it's had such a big effect in only a few months. A visual inspection (or as good as I can do without getting wet) shows minimal slimy growth on the hull, some hairy weeds on the swim platform mechanism (stainless, not antifouled) and what look like small white growths on the prop blades and drive leg housings. Barnacles? Boat is not used as much as I'd like, it's been sitting inactive for weeks so that may have an effect.

I can get the boat lifted and scrubbed off of course, but I was kinda hoping I'd only need that once a year.

Anyone else based on the Hamble having similar issues this year?

Or could this be something else?



PS BruceK my fenders were not dragging in the water.... :)
 
Scala said:
Not those you tie into ropes / lines / whatever. The speed ones. I had loads a few months ago now I'm missing 8 of them, that's 25%.
  • Speed through water on commisisoning in April was 32kts at about 3400 rpm
  • 8 weeks later, max speed was down to 30 kts. Burning 3.8 litres/mile. Tanks full, 2 up.
  • Now after about 4 months I can only get 24kts at about 3000, and fuel burn up at 4.2 litres / mile. Tanks half full, 2 up, so about 250kg lighter.
All at WOT, minimal wind and waves, and so this is not a happy story. Not sure what effect of burning more fuel at lower RPM to go more slowly might have on engine temperatures etc, so yesterday I throttled back to 18kts rather than running any faster.

Must be fouling I assume, but I'm surprised it's had such a big effect in only a few months. A visual inspection (or as good as I can do without getting wet) shows minimal slimy growth on the hull, some hairy weeds on the swim platform mechanism (stainless, not antifouled) and what look like small white growths on the prop blades and drive leg housings. Barnacles? Boat is not used as much as I'd like, it's been sitting inactive for weeks so that may have an effect.

I can get the boat lifted and scrubbed off of course, but I was kinda hoping I'd only need that once a year.

Anyone else based on the Hamble having similar issues this year?

Or could this be something else?


PS BruceK my fenders were not dragging in the water.... :)
Click to expand...

So when new with a clean hull you were attaining 3400 rpm at full throttle ?

Your engines should pull 3500rpm when new with a clean hull , props , drives etc , if this was not the case you have ,

Problems with your engines , or one engine .
Incorrect drive ratio .
Incorrect prop size in relation to either drive ratio or engine horse power.

If that’s the case and you continue to use the boat with something incorrect you will possibly in validate your warranty as there is clearly something incorrect .

when new the boat should have been sea trialed by the dealer or manufacturer, vodia plugged in to read the load against the throttle position , it should have never read 100% . If you have issues already you need to ask for the PDI sheet with the sea trial and see who signed this off , if your saying you only attained 3400 at WOT when new there is clearly something wrong with the set up.
 
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Prop / sterngear hygiene.
More so noticeable if the power plants are just enough clean .
Get a shorty on and snorkel in with a scraper + wire brush .

Mentally I tend to knock 6 knots off , so the FL Targa “ GTO “ 62 which did 31 knots new is really a 24 knot boat ,
Where as a Pershing , Riva or Itama eq 60/62 can top 40 knots , so with that headroom from 24 L V12 s it can afford to loose 6 knots and still be a 30 knot cruise boat .
 
Lift the drives to beach position, get in the dinghy with a scraper and clean the drives and props , you will see a difference in speed and rpm .
 
volvopaul said:
So when new with a clean hull you were attaining 3400 rpm at full throttle ?

Your engines should pull 3500rpm when new with a clean hull , props , drives etc , if this was not the case you have ,

Problems with your engines , or one engine .
Incorrect drive ratio .
Incorrect prop size in relation to either drive ratio or engine horse power.

If that’s the case and you continue to use the boat with something incorrect you will possibly in validate your warranty as there is clearly something incorrect .

when new the boat should have been sea trialed by the dealer or manufacturer, vodia plugged in to read the load against the throttle position , it should have never read 100% . If you have issues already you need to ask for the PDI sheet with the sea trial and see who signed this off , if your saying you only attained 3400 at WOT when new there is clearly something wrong with the set up.
Click to expand...
Hi Paul

Thanks. That's useful. I'll have to double check the RPM at commissioning but I'm pretty sure I was told it was 3400. I wasn't there. I've asked the question.
 
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Paul , has the D4 got nannies burried ECUs programs to prevent overload, excess EGTs ?
Would have thought the opening time’s of the injectors , rpms and a EGT prob info stuffed into a algorithm :) , these days should protect from one of his alloy pistons melting ?
 
Portofino said:
Paul , has the D4 got nannies burried ECUs programs to prevent overload, excess EGTs ?
Would have thought the opening time’s of the injectors , rpms and a EGT prob info stuffed into a algorithm :) , these days should protect from one of his alloy pistons melting ?
Click to expand...
I’d guess his later D4s have the probe in the exhaust elbow however if the prop calcs are wrong from the start no electronic trickery in the world Can compensate the engines having to drive up the steepest hill all there lives , they will run out of breath eventually.
 
8 weeks seems about right until you get a layer of slime knocking speed off your boat.. As each year goes by the antifouling seems to last less and less.
A few barnacles on your prop really do knock the speed down.
i have a light outboard powered boat and really notice the affects of growth. It also reduces max engine rpm .
From a max of 5600 it can drop to 4500 after two to 3 months due to fouling.
 
Scala said:
Not those you tie into ropes / lines / whatever. The speed ones. I had loads a few months ago now I'm missing 8 of them, that's 25%.
  • Speed through water on commisisoning in April was 32kts at about 3400 rpm
  • 8 weeks later, max speed was down to 30 kts. Burning 3.8 litres/mile. Tanks full, 2 up.
  • Now after about 4 months I can only get 24kts at about 3000, and fuel burn up at 4.2 litres / mile. Tanks half full, 2 up, so about 250kg lighter.
All at WOT, minimal wind and waves, and so this is not a happy story. Not sure what effect of burning more fuel at lower RPM to go more slowly might have on engine temperatures etc, so yesterday I throttled back to 18kts rather than running any faster.

Must be fouling I assume, but I'm surprised it's had such a big effect in only a few months. A visual inspection (or as good as I can do without getting wet) shows minimal slimy growth on the hull, some hairy weeds on the swim platform mechanism (stainless, not antifouled) and what look like small white growths on the prop blades and drive leg housings. Barnacles? Boat is not used as much as I'd like, it's been sitting inactive for weeks so that may have an effect.

I can get the boat lifted and scrubbed off of course, but I was kinda hoping I'd only need that once a year.

Anyone else based on the Hamble having similar issues this year?

Or could this be something else?



PS BruceK my fenders were not dragging in the water.... :)
Click to expand...
It’s been a dreadful year for fouling. Just a few tiny barnies on the props can make a huge difference.
 
Its been a hot summer with high light levels and I assume high water temperature where you are moored, and four summer months in the water.

Check again before the lift at speed Max RPM and speed then get it lifted and high pressure washed and clean the props and stern gear or drives and give it a max speed and RPM check after pressure washing.

What boat type, engines drives/ shafts etc and what is the antifouling and when was it applied?

Don't under any circumstances let anyone near your boat with a wire brush and go easy on the scraper!
 
Rocksteadee said:
Have you added anymore gear?
Click to expand...
A new hosepipe, two duvets, and a small vacuum cleaner. I have burned 300 litres of fuel though so that should compensate a bit :)


Bandit said:
Its been a hot summer with high light levels and I assume high water temperature where you are moored, and four summer months in the water.

Check again before the lift at speed Max RPM and speed then get it lifted and high pressure washed and clean the props and stern gear or drives and give it a max speed and RPM check after pressure washing.

What boat type, engines drives/ shafts etc and what is the antifouling and when was it applied?

Don't under any circumstances let anyone near your boat with a wire brush and go easy on the scraper!
Click to expand...
Boat is a hardtop sports cruiser. Had D4/300 / DPH outdrive legs and duoprops. A/F brand not known but two coats applied. I'll organise a lift and scrub ASAP and check again.
 
Also year one of having a boat its essential to check drive anodes and other anodes partway through the season , even hull slime drags you down significantly.

Don't change any other factors such as fueling up or filling water tank between speed/rpm runs.

It's probably hull fouling but check the duo props to see if the gap is the same on both drives between the two props, it could be a slipping bush on one or more props. The easiest way to see a slipping prop bush is the clearances between the props changes.
 
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