Just did a sea trial on a 380 - please advise

[bayboatersf]

I just finished the sea trial on a 2000 Sea Ray 380 with twin 8.1.
Everything went fine except that the boat had trouble reaching 4,400 RPM and when it did the speed was only about 24 knots at the GPS.
We had three people on board with half tanks of fuel and water. The water was calm but I don't know the condition of the bottom of the boat.
I would like to know from 380 owners if this is normal or what I should expect.
Thanks

 

[Alex F]

It sounds like the bottom needs cleaning. Have the seller haul her and power wash the bottom to get her run to the specs.

Check this for reference: http://www.boattest.com/boats/boat_video.aspx?ID=338#Test-Result

Test Results (Printer Friendly Page)

	Range
RPM	MPH	Knots	Total GPH	MPG	NMPG	Stat. Mile	NM	KM	KPH	LPH	KPL	dBA
700	4.5	3.9	2.5	1.8	1.57	446	387	718	7.2	9.46	0.77	60
1000	7.0	6.0	3.4	2.04	1.78	506	440	814	11.3	12.87	0.87	63
1500	9.0	7.8	6.2	1.44	1.26	357	311	575	14.5	23.47	0.61	69
2000	10.8	9.4	11.5	0.94	0.82	232	202	373	17.4	43.53	0.4	74
2500	13.9	12.0	19.0	0.73	0.63	180	157	290	22.4	71.92	0.31	78
3000	19.1	16.6	26.0	0.73	0.64	181	158	291	30.7	98.42	0.31	81
3500	26.6	23.1	33.2	0.80	0.70	198	172	319	42.8	125.68	0.34	82
4000	31.4	27.3	47.1	0.67	0.58	165	143	266	50.5	178.29	0.28	86
4500	36.4	31.7	60.3	0.60	0.52	149	130	240	58.6	228.26	0.26	89

 

[Throttlejockey]

Agreed, check the bottom. What were you using for speed, GPS or the Tridata paddlewheels? Paddle wheels can be hit or miss. My wheels give me 18-19kts at 3500RPM but my SOG on GPS is giving me 23-24kts. If you are having trouble hitting 4400-4500RPM, you may be overpropped.

 

[skolbe]

Have the props scanned as well. Bad props can drop speed along with the bottom.

 

[Mystic Dreamer]

I have diesel 2001 380, however I can tell you that my boat needs a clean bottom and clean fuel filters to reach max RPMs. Also, my 380 likes a full water tank to balance the weight.

 

[bayboatersf]

Thank you for mentioning the props. I will have them checked.

 

[creik]

8.1 Gas?
We also own a 330 DA with 7.4 Horizons, and it sucks gas like mad. IMO, boats of this size should be diesel powered, or you will die at the gas pump.

 

[Jack380AC]

I recommend an engine survey that includes compression check.

 

[Dasch Boat]

You should also check that the exhaust manifolds and risers have been replaced, the originals were aluminum and you don't want them on a salt water boat.

 

[northern]

A dirty bottom cost us 4 knots at the top end at the same RPM. The high RPM fuel burn is what I do, but the low RPM fuel burn is about 20% less than our boat. We travel at 1200 to 1400 RPM and burn 6 to 7 GPH and go 5.5 to 6.3 knots depending on wind. When I purchased my boat I ran it at full RPM until the temp and oil gauges were constant and max speed had been maintained for 5 minutes. make sure owner is not on boat as he will probably be upset with all the fuel you are burning.

 

[Kreole Kid]

It sounds like it has been repowered with newer big blocks. Two of my bb's have a 00' Sundancer 380 and a 01' AC 380, and they both have the original 7.4's in them. Might be something to ask about ....


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[RollerCoastr]

Good point about a re-power. I too would expect to see 454 Horizons in a 2000 model.

 

[osd9]

The gas 1999, 2000 and early 2001 model 380DA had 7.4 motors....some where standard MPI and some where the 380HP Horizons. The 8.1s became available in the 380DA late in the 2001 run. The 8.1 became standard in 2002. All 8.1s were Smartcraft capable, but Sea Ray didn't implement full Smartcraft guages and sensors till the 2003 model 380DA.

 

[bayboatersf]

The boat has been repowered in 2002. I am going to have a full survey next week.

 

[northern]

If you could find the hours on the original motors and why they were removed it might give you an idea how the rest ofthe boat is. In my opinion a 2000 should not need new motors unless the person used the boat 300+hours a year or they were damaged. Were the transmissions replaced at the same time?

 

[bayboatersf]

The engines were replaced because the originals had water ingestion. Can the surveyor tell if the risers and manifolds are aluminum or not without taking them off?
Thanks again for your comments and advise.

 

[osd9]

Water ingestion was a VERY common problem with the 7.4s and the old exhaust system.

 

[Kreole Kid]

I believe my exhaust pipes are stainless and the manifolds are some type of blended mold not the older cast iron molds. My mechanic couldn't verify 100% but he assured me I was in good shape. Best thing is to get the engine serial numbers and call Mercruiser and ask them what SHOULD have come on those engines...


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[Southpaw II]

My boat (2001) was repowered in 2003 due to the water injestion issue, under warranty. Have a scanner connected to your engines to verify the actual hours on the 8.1s. Also be aware that the 7.4 powered boats used 21x22 props and the 8.1 powered boats used the 21x23 props. Really only affects top end a little bit, but the 8.1 engine has a bit more torque than the 7.4. In 4 years, I've only had to replace a couple of sensors on the 8.1s. very pleased so far.

Don

 

[Jimmy Buoy]

My boat (2001) was repowered in 2003 due to the water injestion issue, under warranty. Have a scanner connected to your engines to verify the actual hours on the 8.1s. Also be aware that the 7.4 powered boats used 21x22 props and the 8.1 powered boats used the 21x23 props. Really only affects top end a little bit, but the 8.1 engine has a bit more torque than the 7.4. In 4 years, I've only had to replace a couple of sensors on the 8.1s. very pleased so far.

Don

From what I understand, the hour meters don't contain any numbers. They simply read the information from the engine's computers to display engine hours. Your hours displayed on the dash should be correct. That being said, the proper 8.1 diagnostic tool can provide loads of information that will let you know more about the usage of the boat such as percentage of use at various RPM levels. A boat with 90% of it's running time at full throttle might be one on which to pass! (although at the cost of fuel, that is unlikely).

You might be able to test the manifolds with a magnet. If I recall from my high school days, magnets won't be attracted to aluminum, but they sure will to cast iron. The risers are stainless steel. In a salt water environment you don't want to take a chance with these components. If they fail on the inside where it's undetectable, it could cost you a new engine! The manifolds have an approximate lifespan of 5 yrs with salt water use. How will you know their age and condition??