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Volvo penta AQ120B270

i dont mean to be rude or anyt

i dont mean to be rude or anything like that..but... can i have that in simple blonde english please :eek:)
 
"In simple English: Your boat

"In simple English: Your boat is very overpropped and you need to get a smaller prop.
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"
 
Try 15" x 11". By Volv

Try 15" x 11". By Volvo this is not a HS (high speed) prop and mainly designed for non-planning hulls.
The lowest pitch by Michigan seems to be 15" x 13".
Bottom line: Get down mainly in pitch as far as possible.
 
"wow thank you. ok 1 more simp

"wow thank you. ok 1 more simple question.
whats the direct result in having a overpropped boat?

im not being dopey lol well not to much,
iam also taking note of all this in case the situation should arise again in the future.
and to make sure i completly understand :eek:)
thanks again tho your a star"
 
"Result of over prop?
See You

"Result of over prop?
See Your first posting: Can only get 3000rpm (should be 4500-5000).
Next result: Burned down engine, valves ++++++++++++++++++++++++++++++++++++++++++++
+++++++++++++++++++++++++++++++++++++
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"
 
ok thankyou. will get a 15 x 1

ok thankyou. will get a 15 x 11 prop asap :eek:)
im hoping then that this will prob sort most of my prob. anyway first things first.. correct prop lol
thankyou :eek:)
 
"To help you further understan

"To help you further understand, the pitch of the prop means how "steep" they are twisted. I guess that doesn't sound to clear, but the blades have a pitch that displaces water during rotations. If there was no pitch then looking at the prop from the back of the boat the blades would be horizontal to the boat rear, when it spins it would not move the boat because it is not "pushing" water out of the way. As the pitch gets steeper then it starts to displace water and move the boat forward, if it is over pitched then it is like driving a manual car in 4th gear from starting, the engine just doesn't have enough power to turn the wheels. Same with the boat, the engine just doesn't have enough power to turn the prop and displace all that water, so it bogs the engine down and that is why you are stuck at 3000RPM. Lowering the pitch to an 11 as suggested means that less water will be displaced per revolution and therefore the boat will not move forward as far during each rev but the force on the engine is lower so that it can get up to proper RPMs. Hope that clears up the why part
"
 
"yes i fully understand pitch

"yes i fully understand pitch now lol thankyou.
lowering the pitch will reduce the load on the engine causing it to rev up easier/quicker giving less stress on the engine (cos its a heavy boat)
and in turn better engine running, better engine rev range, and faster overall because of the extra revs i have.
correct??

:eek:)"
 
"Maybe not faster in mph, but

"Maybe not faster in mph, but at least the engine gets a chance to survive. On the other hand You might get close to planning speed, and lowering the pitch gets a much easier boat to handle at low speed maneuvering. Lower idle speed and less prop walk (sideways move) when reversing.
Hopefully You find a High Speed version of 15x11.
An alternative might be to contact a prop shop and they might be able to adjust a 15x13HS down to 15x11. (Normally they only do 1" adjustments)."
 
"I think that might put You cl

"I think that might put You closest to the recommended rpm range. But as I mentioned, there are different 'kind' of props. Volvo Penta have 'STD' (standard) and HS (High Speed). I preferr the HS prop in Your application as the STD props are mainly for barges and displacement/house boats. Problem is they do not make 15 x11 in HS only STD. The smallest HS is 15x15. If You have a prop shop, or the dealer might help You, buy a 15x13 and if too heavy, have it down closer to 15 X 11. The 15 x11 will probably max You out at around 15 knots (17 miles), 15 x 13 19 knots and 20+ miles if Your engine handles it which I doubt."
 
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