2009 280 Express cruiser performance question

warrantyvoider

Hi, all.
Well, the new (to us) boat is in the water, and all the initial projects are done.  Over the past couple of weeks, wifey and I have had the privilege of actually ENJOYING the boat, instead of WORKING on the boat.  Overall, it's been a nice experience.  It's my first "larger" boat, and I don't think it'll be my last.
That said, I'm concerned about the performance (or lack thereof) of the boat.  I'm not sure what I have: A small problem with the boat, or unrealistic expectations.  I'm hoping that somebody here can tell me.
The boat has a single 377 MAG MPI.  With ~75 gallons of fuel, a full fresh water tank, and 300 pounds of humans (myself and wifey), I was expecting to cruise  (at ~3600rpm) in the neighborhood of 22-24mph.  What I'm actually getting at that rpm is 16-17mph.  Experimenting with trim tabs and outdrive trim adds about one mile per hour, bringing us to about 18mph.
If ~18mph is what I SHOULD expect, I'd be content with it.  After all, it's a cruiser, and I'll never be in a hurry to get anywhere.  That said, I have a warranty on the drivetrain.  So, if something doesn't sound right to you guys about these numbers, I'd like to get it addressed on someone else's dime.
Thanks in advance, everybody.  I hope this season has been treating everyone well.

MarkB

You should not expect that. Did you get on plane? You normally need to push through displacement cruising at higher rpms with your trim tabs down. After that the speed will shoot up pretty fast and you will be able to cut back rpm to around 3600 to cruise on plane at around 22 to 23 mph. Below this speed you will drop off plane and the speed will come down fast.

warrantyvoider

MarkB said:

You should not expect that. Did you get on plane? You normally need to push through displacement cruising at higher rpms with your trim tabs down. After that the speed will shoot up pretty fast and you will be able to cut back rpm to around 3600 to cruise on plane at around 22 to 23 mph. Below this speed you will drop off plane and the speed will come down fast.

I am indeed getting on plane.  Once I'm up, I cut back to ~3600, and I'm at that ~18mph mark.  Also, I seem to remain on plane at that speed.

MarkB

Your speedo might not be working. Do you have gps speed.

warrantyvoider

MarkB said:

Your speedo might not be working. Do you have gps speed.

Good point.  I should've addressed this earlier.  The speeds I'm quoting are from a couple of independent GPS readings.  
I've also thought that the tach might be flaky.  Is that possible?

Cableguy Greg

I have a 2008 280 with a 377MAG/B3 setup. I can hold plane around 25 MPH GPS with a top speed of 37 MPH. The tach sucks. Mine is all over the place. When I tap it, it changes by 1000 RPM.

MarkB

Wow I'm surprised you are holding plane at 18 mph. Sounds too slow. You sure the gps speed isn't in knots?

seguir

I have a 2009 280 with a 350 Merc 5.7.   I cruise at 4200 RPM and that gets me around 23 to 25 MPH.  I too experimented the first year and quickly learned to keep it on plane I needed to be going at least 20 MPH or 4000 RPM's.   I burn no oil, however if I drop my RPM'S to 3800 I loose plane and the engine struggles resulting in burning oil (first year).   I would not worry about running the boat at a higher RPM. As far as I am concern the 280 should have never been given the option of the 5.7 engine.

seguir

Oh yes, at 16-17mph....you are not on plane and you will burn oil. 

seguir

More tips...my 280 came with a 100 gal fuel tank....I run the boat with approx. 50 to 60 gal's, keep my water to 1/4 and move all coolers to the front. All passengers are require to sit up front till I am on plane.  Other then that we love our boat. 

warrantyvoider

Thanks for all the advice.  We got to the root of the issue this evening.  It ended up being a faulty tach.  My mechanic brother-in-law hooked up his shop tach.  At cruising speeds, the boat tach was off by ~500 RPM (what the boat said was 4100 RPM was actually 3600 RPM).  At 3600, the boat cruised quite comfortably at 23.5 MPH.
BTW, some were surprised at my assertion that I was able to hold plane at a mere 18MPH.  I confirmed it this evening.  At that speed, it's right on the brink of falling off, but I seem to be able to hold it.
Anyway, thanks again for all the sage advice.

redlightning

Faria tach? 

just got my dual tach back from rebuild.  probably should have installed something different. 

warrantyvoider

redlightning said:

Faria tach? 

just got my dual tach back from rebuild.  probably should have installed something different. 

It is indeed a Faria tach.

mattie

Faria guages are more of a guideline.

When the guages are moving - something is happening. That is about the range of their accuracy.

my 2 cents - lol.

raybo3

Faria tachs are bigger than other brands. Mounting them in the existing hole is a problem..... 

MarkB

I replaced my faria tach with a Smart Craft System Tach (Part 46842). It fit right in without the need for a bezel. The next year I replaced the Faria 4 in 1 with a Smart Craft 4 in 1 gauge (temp, oil pressure, gas level, etc.) and I needed to add the chrome bezel to fil up the hole. They both look like factory install now.  

 

seguir

Mark, how difficult are these to hook up....can I get a picture of your dash?

MarkB

Well my mech did it, and I think the System Tach Gauge and all the wiring to the Mercruiser was less than $1000. I added the 4 in 1 gauge after that, I think that was around $350. The 4 in 1 was very easy to install. Once the system tach gauge is in, you plug another gauge into the back of that gauge and the digital signal just goes to the next gauge. If I want to add another gauge I just plug into the back of the 4 in 1 and just keep daisy chaining them. The wires act as a bus with all digital info, and the gauge just pulls the data it needs to present the condition.

Here's a picture of my helm. The smartcraft system gauge is just behind the Lowrance Fish Finder (smaller one) and the 4 in 1 is just next to it. They both light up at night as well when I turn my nav lights on and engine is running.

seguir

Thanks Mark, looks like the same config as the280.  Its something to consider as I am now not trusting my gages.

jbschmalz23

Mark, where did you find the 4 in 1 guage? Do you have the part number for that? Also, how hard of a job is it to change to SmartCraft guages. I would love to upgrade the guages on my 280 this winter!! Yours looks great!

MarkB

I did it through my mechanic. I don't think it is hard at all if you have an MPI engine. You just plug into a harness and get all the signals. The gauges of course are really easy to install. You need to install the system gauge before you can hook up the other gauges like the multimate function. They just daisy chain together after that.

The products can be found in this brochure.
https://www.google.ca/url?sa=t&source=web&rct=j&url=http://mercurymarine.co.za/files/brochures/8m0063378_2012gaugectlg_lr2_0.pdf&ved=0ahUKEwjrr63rs7zJAhVHdh4KHT5LBbUQFghOMA0&usg=AFQjCNGDVEWzaaL9_sB74gO2ks2l5U9CEw&sig2=rRGQ3UmX0fXBn1yOlX7eyQ

Cableguy Greg

jbschmalz23 said:

Mark, where did you find the 4 in 1 guage? Do you have the part number for that? Also, how hard of a job is it to change to SmartCraft guages. I would love to upgrade the guages on my 280 this winter!! Yours looks great!

A part number would be great. I would like to change mine as well.

Cableguy Greg

I guess I should have looked deeper... Here is the part number. 8m0052879

MarkB

I assume you got that off the brochure in the link I posted?

jme097

I would definitely like to replace my Faria 4 in 1 gauge without a doubt. Besides for the 8m0052879, do I need another harness? I already have the 6.2L MPI engine with smartcraft; just all original gauges. 

Handymans342

Did you know Faria is warrantied for life?

jme097

For real? LOL. 

Handymans342

Thats what my marina said but hard to believe.

TonyWalker

I have had a couple of tachs replaced by Faria, no questions asked.  Finally got a pair of them that work pretty good although I still need to to the Faria tap occasionally.

jme097

Yeah I don't even want to bother with them anymore. I'd rather have the Merc's and have more information available. 

Handymans342

I unfortunately have no other choice.