410 Performance problem

My advice is to change your second to last sentence inpost #59 from:

"We leave on Friday from Ponce INlet to go to the Bahammas for 2 weeks and I hope we have got everything right."

to

If (and only if) everything checks out and the boat performs up to specifications we will leave...
 
Did you see the boat when you just hauled it? Granted, taking a diver's "word" for it might be a mistake, but if you saw it yourself- and it was squeaky clean- I'm not sure why they would say that was the culprit.

With that said, I just found out how sensitive the engine loading is on my boat. A few weeks ago on an offhshore fishing trip my engines performed poorly- a little smoke, soot on the transom, and the engines wouldn't turn over 2600. Not having the time to troubleshoot "one at a time", I changed the Racors (discolored black, but no slime/gunk or water). I also had a couple month's worth of "slime" on the bottom- no hard growth, just slime 'cause I was too lazy to clean it. After taking an hour to scrub the bottom clean as a whistle last week I took it back out last weekend 50nm offhsore and she ran great- I was surprised that some slime on the bottom would make that much of a difference. I still seem to have "lost" 80 rpm (2720 instead of 2800 WOT), so I'm probably gonna take some pitch out of my spare props and swap 'em out. Good luck and let us know...
 
Update:
I took the boat out this afternoon and here are the results.
2800 RPM on analog starboard gauge.
2725 RPM on analog port gauge.- Not sure about this but the sync needle is dead center,
Top speed 30 MPH
Cruise speed at 2375 RPM 22.8 Knots or 26.5 MPH
Remove, repitch, prop scan and replace props- $1000.00
Clean fuel tanks and all lines, replace fuel filters and racors, sea trial with CAT mech.- $1500.00
Pull off aftercoolers and have them steamed and reinstalled- $1,650.00
Have boat hauled and bottom sanded and repainted- $1,300.00
Reaching the desired RPM and almost desired speed 2 days before Bahamas trip- PRICELESS
So now I need to work the props to try and achieve the desired speed of 32 MPH? And does anyone that currently owns a 410 Sundancer have their current weight?
 
21,000 lbs dry. Work the props to get 2850PM on each engine with a digital tach. Speed will vary with weight of the boat (loaded with fuel and provisions, etc.).

Do you plan on running at 32 MPH (27.8 knots) all the time?
 
Sea Ray always lists their boat's dry weight with standard propulsion and equipment. The 22000 lb weight that is indicated in you owners manual would be correct if it has gas engines. Since you boat has diesels your weight would be 24500 lbs. Add to that figure for options your boat may have such as bow thruster, all chain windlass, hardtop etc.


Hope this helps
 
Glad to see you are getting to where you need to be. You don't mention your load (fuel, water, stuff) in your final runs.

I would suggest you buy a hand held laser tach (you can get them on ebay for under $30) to check the accuracy of your tachs. I would lean to the side that the factory analog tachs are not accurate. I replaced both of my analog tachs with Aetna digitals and they are dead on. You can really dial in on your comfortable cruise RPMs with these digitals....you just need to catch your self sometimes being too anal over a few RPMs.

Now that you have a known clean bottom, aftercoolers, etc, etc., I would load up the fuel tanks, water tank, stuff and grab a few buddies and then go make a run to see your WOT. If you are going to use a laser tach, and run with the hatch open, bring some ear plugs....those roaring cathedrals of torque sure to make some noise.....

FWIW...you cruise numbers are VERY similar to what I have right now on the same year/model 410DA......I'm very happy with the performance and economy!!!!!

Good luck
 
5,500.00 wow, how much is the next 2 mph going to cost?

At least your sleeping through the night now.lol
 
Well done. How is the Smartcraft digital readout compared to analog tachs compared to "lasers?" My Smartcraft lines up pretty well with my analogs. Are they just a repeater? Although, I have had my port tach act up in the past, and the Smartcraft read just right. Apologize for the creep/theft.
 
Ah, yes. Ain't the trial and error stuff fun?
Main thing is they're running well and you've only got some minor "tweaking" left to do...
The speed you desire just may not happen for whatever reason. As long as your motors turn up to rated RPM (one does, one's real close) when you're loaded that's all you can do. I don't see any way to increase your speed at this point because if anything you want to remove a little pitch to increase your rpms a bit- which will slightly reduce speed.
Enjoy your trip! Always wished I lived on the right coast so I could make that run...

BTW- I'm curious about the prop scan- I need to have a little pitch removed- how much is the prop scan, and do you recommend it?
 
tobnpr said:
BTW- I'm curious about the prop scan- I need to have a little pitch removed- how much is the prop scan, and do you recommend it?
Click to expand...


I've had my props prop scanned locally in NJ and the cost was $275 per prop. I don't have the paper work with me, and forget the actual numbers, but are scanned to some ISO standard to a ridiculous tolerance of .001 or so....pretty darn near perfect. Yes I recommend it! One note of caution.....how you install the props is very critical to maintain that tolerance. Jamming in a block of 2X4 to hold the shaft while tightening down the jam nuts may cause the props to flex and thus compromise the tolerances.

Hampton said:
How is the Smartcraft digital readout compared to analog tachs compared to "lasers?" My Smartcraft lines up pretty well with my analogs. Are they just a repeater? Although, I have had my port tach act up in the past, and the Smartcraft read just right.
Click to expand...

The analog tachs and the smartcraft digital tach readouts, from my understanding, get their signal from the same source on the 8.1s. It's the analog guages themselves that, IMHO, suck! The tachs on every twin engine boat I've owned (all SeaRay) have 'acted' up on me. I've replaced more tachs than I care to remember. My 380DA had the tachs replaced by the previous owner, and then I replaced one of them again. They just don't seem to be very reliable....again....IMHO based on my experiences. Your smartcraft readouts are a much more reliable way to read your RPMs. But, that is not to say that they are accurate...just reliable. They can also be out of calibration. That is where a calibrated laser tach comes in. You can use the laser to check the calibration of the digital tach.
 
tobnpr said:
........ I don't see any way to increase your speed at this point because if anything you want to remove a little pitch to increase your rpms a bit- which will slightly reduce speed..........
Click to expand...

Not necessarily. From what I'm reading, Dkruid 410 is now looking to maximize his WOT 'speed'. Based on his posted numbers, he may not have yet achieved full rated WOT RPMs. If he reduces his pitch it will increase his WOT RPMs, and then his WOT speed 'may' go up with the increased WOT RPMs. His cruise speed, at 2350 RPM, 'will' go down, so he will have to increase his cruise RPMs if he wants to maintain the same cruise speed.....all the time being mindfull not to cruise above the recommended cruise RPMs.....2400 as per CAT.
 
osd9 said:
Not necessarily. From what I'm reading, Dkruid 410 is now looking to maximize his WOT 'speed'. Based on his posted numbers, he may not have yet achieved full rated WOT RPMs. If he reduces his pitch it will increase his WOT RPMs, and then his WOT speed 'may' go up with the increased WOT RPMs. His cruise speed, at 2350 RPM, 'will' go down, so he will have to increase his cruise RPMs if he wants to maintain the same cruise speed.....all the time being mindfull not to cruise above the recommended cruise RPMs.....2400 as per CAT.
Click to expand...

OK, I see what you're saying (I think)- it's then a matter of "whether" the increased rpm's more than offset the "less movement through the water per turn", which would increase top end...right?
 
After reviewing this thread I'm wondering if spending all that money was necessary.

Dude, take a look at post #2 you had the right answer 1 hour and 7 minutes after you asked the question.......... and it was free.

"Clean the bottom" and in post #59 "need to clean the bottom".
 
ImpulseIII said:
21,000 lbs dry. Work the props to get 2850PM on each engine with a digital tach. Speed will vary with weight of the boat (loaded with fuel and provisions, etc.).

Do you plan on running at 32 MPH (27.8 knots) all the time?
Click to expand...


No not all the time but I would like to be able to reach it. It may never happen and I most likely won't go crazy trying to reach it but, since I have a spare set of props, I will try and perfect them if I can.
 
osd9 said:
Glad to see you are getting to where you need to be. You don't mention your load (fuel, water, stuff) in your final runs.

I would suggest you buy a hand held laser tach (you can get them on ebay for under $30) to check the accuracy of your tachs.

FWIW...you cruise numbers are VERY similar to what I have right now on the same year/model 410DA......I'm very happy with the performance and economy!!!!!

Good luck
Click to expand...

Thanks Dominic. This site you lead me to has been alot of help as have you. I am going to get the laser tach just to ease my mind and I think I seen a picture of your digital tachs you put in on another thread :thumbsup:. Very nice. Since I have another set of props I will try and work them. The current ones that are on it are 21.75X 21.75. The others are still factory.
 
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