Cruise Speed 38DA vs 380 DA

Brutus C Paw

Brutus C Paw

Member
Mar 27, 2009
214
Ocala, FL
Boat Info
2007 38 Sundancer;
1999 Mariah 182 Shabah Bowrider
Engines
8.1S Horizon 370HP;
4.3L Mercruiser 190HP
We just finished 10 days on Lake Michigan on our 2007 38 DA with 8.1 Horizons. This is its second season in the water; finished the week at just over 100 hrs. We cruised with a 2000 380 DA with 7.4 - 370 HP. We were comfortable at about 3800 rpm which was about 26.0 to 26.5 mph. I played with the tabs and this seems to be the best performance. My running mate in the 380 was only doing about 3500 + rpm. We store and dock at the same place and have been in the water the same, no prop scans have been done, but we think we both will get them done soon. Just curious what you think about the reason for the difference in rpm and speed. Any other 38DA owners have data?
 
Just a guess but it may be the prop pitch/size and the trans ratio.

Just a guess...

Doug
 
My boat has the 21X22 4 blade props and cruises best for me at about 3500 rpm. This usually puts me at 21.5 knots (24.7 mph). This is with tabs down.

The data I have from SR on the 1999 models say the 380 DA came with the same 21X22 props and the 2.5:1 V-Drive as I have. Since SR has changed their website, I can't find the archives that I used to see, but I recall that the 2007 boat is significantly heaver than the 18,300 lbs. dry weight of mine. In addition to the difference in hull design, weight may be the other factor.
 
I have looked for transmission data on the 2000 versus my ZF's, but haven't found any. It seems I plane easier. I know I'm about 1000 pounds heavier plus the admiral keeps her pretty well loaded when we are on trips, but I thought the 8.1's versus the 7.4's, although HP about the same, and new haul design would give the newer boat some advantage. I was burning about 10 to 15% more fuel due to the higher rpm - right at 0.7 mpg
 
. Just curious what you think about the reason for the difference in rpm and speed. Any other 38DA owners have data?[/quote]

Seems maybe a little slow on speed and high on RPM..What is your WOT RPM?
 
I have to admit I've never pushed past about 4000 rpm - which gets me to almost 28 mph. Your 360 is the same LOA and beam with 8.1's, what do you see?
 
Brutus C Paw said:
I have to admit I've never pushed past about 4000 rpm - which gets me to almost 28 mph. Your 360 is the same LOA and beam with 8.1's, what do you see?
Click to expand...

Your boat is listed as being a little heavier than mine, however; variables in water and fuel load can put us even. That said, my numbers are:
3400 / 25+/- MPH
3800 / 29+/- MPH
4000 / 31+/- MPH
My fuel burn is about the same at 3800 as yours. (I like to run at 3400). Also like you, I rarely run WOT. Mine will do 4650 RPM fully loaded, which is a little high (4200 - 4600). Eventually I may add a little pitch,say .5 to 1".
I would say that if your wot RPM's are where they should be, it is what it is, but if they are high, a pitch change may be in order or if they are found to be out of spec, then bring them to where they should be. I read somewhere that on boats in our class, 1" is good for about 200 RPM. Others on this site may have a better feel for that.
For what it's worth, I have a friend with a 2003 380, same motors,trannys,and props as mine and we run basically identical RPM's and speeds and those 380's are bigger boats than ours so I am not sure how much weight and drag affects these power packages.
My numbers, my friends numbers and your friends numbers are pretty close, your numbers are slightly different, so I would start with the WOT spec and go from there. This is my first year with this boat, 8.1's and v-drives, I'm still learning so let me know how you make out and enjoy your boat
 
I have a 2007 38'. The 2000 380 is now the 2007 40' SeaRay The beam is 6" narrower in 2007 and 2 feet shorter, That is why you see a difference
 
Wasn't the dead rise of the older models less? I don't know if it applies to this line of boats, but others in that time frame had less dead rise, so they planed easier, cruised with lower fuel consumption, and rode much rougher.
 
The older 380DA and the newer 38DA only share two things in common....the '3' and the '8'.....well....maybe the 'D' and 'A' also. Other than that, they are completely different boats...from hull design to arch/hardtop, engine, transmission, weight, length, etc.....comparing the two, although similar in size/arrangement, is not a fair comparison.

BTW....the older 1999-2004 380DA isn't really the current 40DA....it's more like the newly designed 390DA/40DA 'replaced' the 380DA......as the current 38DA 'replaced' the older 360DA.
 
the dead rise on my 360DA is 21 degrees, I believe the 38 (not the 380) is the same
 
Last edited:
my3sons said:
Your boat is listed as being a little heavier than mine, however; variables in water and fuel load can put us even. That said, my numbers are:
3400 / 25+/- MPH
3800 / 29+/- MPH
4000 / 31+/- MPH
My fuel burn is about the same at 3800 as yours. (I like to run at 3400). Also like you, I rarely run WOT. Mine will do 4650 RPM fully loaded, which is a little high (4200 - 4600). Eventually I may add a little pitch,say .5 to 1".
I would say that if your wot RPM's are where they should be, it is what it is, but if they are high, a pitch change may be in order or if they are found to be out of spec, then bring them to where they should be. I read somewhere that on boats in our class, 1" is good for about 200 RPM. Others on this site may have a better feel for that.
For what it's worth, I have a friend with a 2003 380, same motors,trannys,and props as mine and we run basically identical RPM's and speeds and those 380's are bigger boats than ours so I am not sure how much weight and drag affects these power packages.
My numbers, my friends numbers and your friends numbers are pretty close, your numbers are slightly different, so I would start with the WOT spec and go from there. This is my first year with this boat, 8.1's and v-drives, I'm still learning so let me know how you make out and enjoy your boat
Click to expand...
I get about 23-23.5kn at 3600rpm. Sounds really nice at that speed. I can however reach 32kn @ 5000rpm, but don't dare run like that a lot. I have 8.1s, 2.5ZF, 21x23 4 blade NIBRALs. The spares are 22x23 but not much difference. I would like to try 22x25, and see if I can lower my WOT. If anyone has some, I'd be interested in a trade.
I also get .75mi/gal at a normal cruise speed.
 
Yikes!! All I know is that we usually keep it at 2500 to 3000 rpms which puts us at 21 kts because any higher, and the fuel consumption goes to 35+ gal/hr and my sweetie gets chest pains when he sees that....
 
Having owned a 2002 380DA with 8.1s, I find it difficult to accept that you can maintain 21 kts at 3000 RPMs and I would contest that it is impossible at 2500 RPMs.
 
Just to update the thread, we took her out on the lake last weekend for our first WOT. The results were 4620 per the Smartcraft and 33.8 mph on the E120. We had just fueled so this is with the full 250 gal, full water, and our summer gear.
 
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