2006 Regal 3880 w Volvo 8.1-Prop Pitch and Cruise

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boatlover14

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Joined
May 31, 2009
RO Number
31341
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I purchased a leftover 2006 3880 in June 2009. Volvo gave me a 2 year warranty as long as I cut the props down to 22 X 21 and installed a plate within each exhaust hose. I am wondering what others are using for pitch on the 2006 model, and what their cruise is at 3500
 
I have a 2007 4080. Same boat, same engines.
My props are 22 x 21 with no cup.
I cruise at 3800rpm as these are HO motors, that gets me about 23knots.
Not sure what 3500rpm would get me, probably 18knots.

What was the purpose of the plate?
My exhaust is under water below the boat.

Good luck with the boat.
If you have any questions, just ask.
 
The plates were requested to prevent backflow of water at idle after the engines had been cruised for a while. They were installed about 18 inches from end of exhaust hose. I was informed that Volvo extended warranties on earlier models that installed these.
According to Regal's site, the 2009 version wtih the Volvo 8.1 cruised 22 knots at 3500. I only had 18 knots at this cruise.
 
You can't go by the numbers Regal publishes.
They are perfect conditions, limited load, no bottom paint, no growth, no wind, etc.
I don't know any manufacturer that publishes true numbers for the type of boating most of us do.
Sounds like your 18knots jives with mine, so thats it.
Cruise at 3800, its more fuel efficient.
Cruise for a gas boat should be about 3/4 of full throttle.
Full throttle on my motors is 5000 X .75 = 3750
 
We were now reaching WOT on ours. We had 2" of pitch taken out and added 1" of cup in September. This got our RPMs up and she now cruises nicely at 3600 - 3800 and we got WOT of 4500, but we lost a lot of "bite" around the dock for docking.
 
Boatlover14, what was the prop size originally? Did Volvo say why they demanded the reduction?
 
Dave, at what point do the secondaries open on your motors? I would think that running a lower RPM so the secondaries stay closed would be better on fuel..If I had to guess Id say the secondaries open at 3200rpm??
 
The newer engines might be MPI.

I have an old pair of 305 GM engines. My secondary's are closed at 3200 rpm.
My fuel flow meters start going up pretty good at 3500 rpms.
 
Oh right, good call on the MPI.

I bet your 305's sound sweeet though..
 
quote:
Originally posted by MrsRobinson

We were now reaching WOT on ours. We had 2" of pitch taken out and added 1" of cup in September. This got our RPMs up and she now cruises nicely at 3600 - 3800 and we got WOT of 4500, but we lost a lot of "bite" around the dock for docking.

Click to expand...


Isn't that a high cruise RPM for that engine?
 
quote:
Originally posted by CurrentSea

What is a secondary?

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When you have carburetors, the secondary allows more fuel into the carburetor when you are cruising at a higher RPM.
 
quote:
Originally posted by boatlover14

The plates were requested to prevent backflow of water at idle after the engines had been cruised for a while. They were installed about 18 inches from end of exhaust hose. I was informed that Volvo extended warranties on earlier models that installed these.
According to Regal's site, the 2009 version wtih the Volvo 8.1 cruised 22 knots at 3500. I only had 18 knots at this cruise.

Click to expand...


As Dave mentioned, those numbers are a reference point. Wind, Tide, bottom condition, and weight in the boat (fuel, water, people and all the crap you keep on the boat) will make those numbers change.

Do you have the "H.O. 8.1 motors?
 
quote:
Originally posted by KiDa

quote:
Originally posted by MrsRobinson

We were now reaching WOT on ours. We had 2" of pitch taken out and added 1" of cup in September. This got our RPMs up and she now cruises nicely at 3600 - 3800 and we got WOT of 4500, but we lost a lot of "bite" around the dock for docking.

Click to expand...


Isn't that a high cruise RPM for that engine?

Click to expand...


Those are Merc Horizon engines with rpm rating up to 5100
 
Yeah David (Kida), what Gary said.

;-)

David, where is Saint Max slipped now? Any luck selling her?
 
OH. Didn't know the 8.1 spun up that high.

I'm at River's Rest on the Chick. Slip C-4. I told Charlie (the owner) if someone is looking for a 330, show it. Otherwise I'll use it. Between fuel and the economy, I would take a HUGE bath on her despite putting 30% down on '07. OH Well. It is what it is.

Wish it would sell. There is a beautiful 50' Viking for sale on D dock. You can eat off the engine room floor. Asking price is $460K. I'm only $440 short!
 
David, we could go in as partners, but we'd still be $420 K short.
 
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