Sundancer ACTUAL weights

[Joshieburger]

Appreciate all the info so far anyone else have their boat’s actual weight?

 

[Scott215]

Yes 2006 215 weekender 5000 pounds dry.

 

[Stee6043]

thanks for the reply and the info. Was that on your 340? Those are the numbers id like to see. I really dont mind just putting around “cocktail cruising”, but 5mph is a LIIIITTLE slow haha.

Nah, scratch that comment I made actually. I looked back at that photo and I was headed downstream in a river when I snapped it, that's reporting GPS speed. So I'd bet I am closer to 6mph when on a lake with no current @ 1100ish RPM.

That photo is from my 400. Same motors, similar performance to what I got from my 340. Though my 400 has always gotten on plane (and stayed on plane) better than my 340 ever did...

FWIW nobody with gas engines in a cruiser runs around at idle speed. It's "no wake speed". I like to use the term bare steerageway...I cannot turn particularly well at anything below 5kts

 

[Joshieburger]

FWIW nobody with gas engines in a cruiser runs around at idle speed. It's "no wake speed". I like to use the term bare steerageway...I cannot turn particularly well at anything below 5kts

im a new member, but not a new boater, but understood.

 

[Scott215]

Yeah steering doesn't work very good with no throttle

 

[Joshieburger]

Welp… got the old props off and threw 17x17s on. When the diver left i got another (quick) better look at the props that came off. Measured them. They ARE in fact 17” diameter. But looks like stampings say 18 pitch. So i was actually OVER pitched which may be why it was harder to get on plane, and explains a few rpms on the starboard… i still dont know why “12 15” is stamped on the side… just to confuse people of what size they have?

 

[Golfman25]

Welp… got the old props off and threw 17x17s on. When the diver left i got another (quick) better look at the props that came off. Measured them. They ARE in fact 17” diameter. But looks like stampings say 18 pitch. So i was actually OVER pitched which may be why it was harder to get on plane, and explains a few rpms on the starboard… i still dont know why “12 15” is stamped on the side… just to confuse people of what size they have?

I thought you were hauled out? That extra inch should cost you about 150-200 RPMs. Is that what you saw on the starboard engine?

 

[Joshieburger]

I thought you were hauled out? That extra inch should cost you about 150-200 RPMs. Is that what you saw on the starboard engine?

I was hauled out last year. Its in the water currently. And no, it was definitely lower than 200 rpm less (i want to say 3300-3500 is the most i saw). But again, with my port side just being a mess of drag, i can understand it dogging the stbd as well.

ill try to upload a picture of the prop that made me think it was a 12x15

 

[Joshieburger]

 

[Yendor]

. . . i got another (quick) better look at the props that came off. Measured them. They ARE in fact 17” diameter. But looks like stampings say 18 pitch. So i was actually OVER pitched which may be why it was harder to get on plane, and explains a few rpms on the starboard… i still dont know why “12 15” is stamped on the side . . .

Odd. You'd have thought that somebody in this crowd would have figured that out.
Oh, that's right . . . somebody did. And not one like, from anywhere in the crowd. ???

Quite the conundrum for sure.
In any case, it hardly seems likely that starboard engine could/would seem to be operating normally IF it where in fact only turning half the prop that it should be; it should/would readily over-rev.

Conversely, if the prop were a 12x15 and the engine IS operating normally, putting a 17x17 on there would choke it nearly to death and render regular operating rpm range, completely unattainable. As such, there would seem to be a discrepancy here, above and beyond the weight of your boat.

This would all imply to me that the numbers you got of the current prop(s) were not what you presumed them to be. Whether you misread those numbers or they are something other than the diameter/pitch (model # ?), I don't know, but there is something here that doesn't jibe, and it looks to me like that doesn't involve the weight of the boat.

FFS.

 

[Joshieburger]

Odd. You'd have thought that somebody in this crowd would have figured that out.
Oh, that's right . . . somebody did. And not one like, from anywhere in the crowd. ???



FFS.

You win? Lol anyway…

Right, i never argued the math of larger prop = lower rpm of course, but A: wouldnt a heavy boat also lower rpm because of the motor’s inability to push the weight? And B: what the heck does R12 15 on my prop mean then?

still doesnt solve my issue of wondering if my weight is ok in comparison to others. If I can get an answer on that, then motor performance is my last mystery to solve.

 

[Golfman25]

You win? Lol anyway…

Right, i never argued the math of larger prop = lower rpm of course, but A: wouldnt a heavy boat also lower rpm because of the motor’s inability to push the weight? And B: what the heck does R12 15 on my prop mean then?

still doesnt solve my issue of wondering if my weight is ok in comparison to others. If I can get an answer on that, then motor performance is my last mystery to solve.

Fir what it’s worth, I think your weight is within spec. Based on what others have said. Not that far off.

 

[Joshieburger]

Fir what it’s worth, I think your weight is within spec. Based on what others have said. Not that far off.

Thanks! Its worth a lot, thats what this thread was for.

 

[sbw1]

Not sure it matters what other people’s boats weigh. If the Travel Hoist says you weigh 15,000 pounds, that’s what you are pushing through the water. Very odd set up with mismatched motors. I would try to address that issue first and then deal with props after the power is symmetrical.

 

[Yendor]

Fir what it’s worth, I think your weight is within spec. Based on what others have said. Not that far off.

Realistically, there isn't any reason to be overly concerned with not knowing its weight, most don't.
When you get it to perform as it was designed to, that number will be of no consequence.

Now that you have the right props on it, you can assess how far off you are from where it ought to be.
Not that you want to hear it again, but the first thing you should do in your quest to regain your missing designed performance is to loose that carb and get rid of the intrinsic mis-match that will ultimately have to be dealt with.

 

[Joshieburger]

Thanks.

I wouldnt mind starting a separate thread discussing the drawbacks of not having both motors being fuel injected. I feel i could put up a compelling argument that, however unconventional, odd and unpopular it is, having two motors rated at 310hp each, with the same W.O.T. Rpm rating, same displacement, same heads, same internals… but one uses a computer to calculate how much fuel to throw into the motor (and is therefore of course more fuel efficient), and one uses a carburetor to throw fuel into the engine (being less efficient), can and will still yield the same power at both cruise and WOT. There are some pretty seasoned carbers out there that can dial in a carb perfectly and possibly only have a negligible difference in fuel efficiency…

what I am saying is I know having a carb/efi combo is odd and everyone will double take, but my fuel delivery MAY just not be as big of an issue as everyone thinks it is. Im willing to bet that 8/10 owners “twin” engines have the same difference in performance between their two motors… with ALL the variables out there such as clogged/dirty injectors, weak spark, drivetrain friction, etc.

With the stbd motor being original i would almost argue my carb motor is potentially performing better than the FI. I think, again, the biggest thing ill have to worry about is not being able to advance the throttles evenly as OF COURSE, fuel delivery should be smoother with FI.

when I get the carb to reach WOT, I can reassess how much of a difference there is between the two regarding performance.

 

[scoflaw]

Different timing curve most likely would effect acceleration but WOT should be equal.

 

[Yendor]

Thanks. I wouldn't mind starting a separate thread discussing the drawbacks of not having both motors being fuel injected. . .

That is a very good idea as that is now the subject of the thread.
It would save reading two pages of what is no longer really relevant.

Your premise that there is not a functional difference is based entirely on one data point; wide open throttle.
Now consider if you will, What percentage of the time will you be running wide open throttle?

If all of your assumptions about the internal similarities are true, then I would be more inclined to agree.
It seems unlikely to me that with the changes made to accommodate and successfully run MPI, that MerCrusier
would have skipped the completely painless step of grinding a new cam for the effort. This could be confirmed or denied by running your engine numbers and seeing if they do in fact have the same cams. I suspect they do not, but I haven't even stayed at a Holiday Inn Express since I can remember.

IMO, knowing that little tidbit of information would probably be a good starting point for that new thread.

 

[Joshieburger]

That is a very good idea as that is now the subject of the thread.
It would save reading two pages of what is no longer really relevant.

Your premise that there is not a functional difference is based entirely on one data point; wide open throttle.
Now consider if you will, What percentage of the time will you be running wide open throttle?

If all of your assumptions about the internal similarities are true, then I would be more inclined to agree.
It seems unlikely to me that with the changes made to accommodate and successfully run MPI, that MerCrusier
would have skipped the completely painless step of grinding a new cam for the effort. This could be confirmed or denied by running your engine numbers and seeing if they do in fact have the same cams. I suspect they do not, but I haven't even stayed at a Holiday Inn Express since I can remember.

IMO, knowing that little tidbit of information would probably be a good starting point for that new thread.

I guess you win again? You mentioned another component that is different between the two motors. Sorry, I just want to clarify as it’s hard to tell through all your condescending replies; you’re saying the only time the 2 7.4 motors match power outputs are at WOT? Because again, I am willing to bet that i can synchronize both at cruise rpm, set my rudders straight and still achieve a straight line regardless of what cams mercruiser put in to allow both motors to make 310hp.

btw i have no desire to keep feeding insulting replies or insult anyone’s intelligence, just talking things out and brainstorming ideas. Once again to bring it back to my original reason for the thread, i want to make sure that I can expect my boat to perform the way the manufacturer intended (and let me cover myself here) ASSUMING my motors were identical, and produced the same power. If I know everything else is within spec, i dont need to chase ghosts, just need to focus on the motor(s). Taking motors out of the equation, weight, i believe, is the biggest variable that i could have from other hulls, which is why that was the subject of my thread as there was a big discrepancy from the manufacturers net wt vs scale weight on these. Also may help others if they are trying to size boat lifts, cradles, etc. for them to realize their weights may be SIGNIFICANTLY higher than they think.

 

[Stee6043]

I guess you win again? You mentioned another component that is different between the two motors. Sorry, I just want to clarify as it’s hard to tell through all your condescending replies; you’re saying the only time the 2 7.4 motors match power outputs are at WOT? Because again, I am willing to bet that i can synchronize both at cruise rpm, set my rudders straight and still achieve a straight line regardless of what cams mercruiser put in to allow both motors to make 310hp.

btw i have no desire to keep feeding insulting replies or insult anyone’s intelligence, just talking things out and brainstorming ideas. Once again to bring it back to my original reason for the thread, i want to make sure that I can expect my boat to perform the way the manufacturer intended (and let me cover myself here) ASSUMING my motors were identical, and produced the same power. If I know everything else is within spec, i dont need to chase ghosts, just need to focus on the motor(s). Taking motors out of the equation, weight, i believe, is the biggest variable that i could have from other hulls, which is why that was the subject of my thread as there was a big discrepancy from the manufacturers net wt vs scale weight on these. Also may help others if they are trying to size boat lifts, cradles, etc. for them to realize their weights may be SIGNIFICANTLY higher than they think.

I think we can all agree that we can't wait to hear how this thing runs! And hey, share some pictures when you have time.

FWIW - it looks like the 96 carbed version will not share the same timing gearset as the 97 FI. I wonder if that's something you might notice as you move through the RPM's? Everything else certainly looks very similar.