CIVID Boating

LaRea

And I snagged this screen shot on the way home.

PickleRick

My boat has to be on a trailer to do 41 mph.

rasbury

Mine too!

reneechris14

@LaRea I think I see a pattern here 1st time out each year you put it to the pins, good for you. Those 496's must sound sweet at the spot.

Aqua_Aura

How many rpm are you running to get that? And what's your normal cruise on plane rpm? 

PickleRick

The 235 came with i think 3 or 4 different engine packages. The 5.7 was the big option with either a volvo penta dp or bravo 2.  

I believe the bravo 2 would have better top end and i think was rated around 38 mph top speed.  

Mine was the lowly 5.0 alpha 1 with a 5.7 replacing it sometime later. 

Dream_Inn

PickleRick said:

The 235 came with i think 3 or 4 different engine packages. The 5.7 was the big option with either a volvo penta dp or bravo 2.  

I believe the bravo 2 would have better top end and i think was rated around 38 mph top speed.  

Mine was the lowly 5.0 alpha 1 with a 5.7 replacing it sometime later. 

Oh boy, did I hear Bravo 2??  I will soon have my 496s humming and hit close to 45mph...always good to hit it once or twice a year
@LaRea just a bit jealous man!!  But soon.  Love the pic!

69fastback

The little 232 will GPS about 54 with the 350 Mag. 

PickleRick

I could hit 44 mph  in the rinker if you let me borrow one of those 496 motors. I promise to give it right back, this alpha of mine will last maybe a week.

 

LaRea

Aqua_Aura said:

How many rpm are you running to get that? And what's your normal cruise on plane rpm? 

I'm only getting around 4200 RPM at WOT.  Ideally, the 496 should hit 4400-4800, so I'm slightly over-propped.  I could benefit from re-propping with a shorter pitch, but I'm definitely not complaining about performance.  Normal cruise is 30-32 mph at 3700 RPM.  

@reneechris14 -- great observation!  I guess I do feel the need for speed on that first time underway in the spring!

PickleRick

Aqua_Aura

Thanks @LaRea just curious for reference. I have the single 496 and get on plane at 3200 rpm and go about 25mph on my 280. I have never had it more than that. 

LaRea

If your boat is like most Rinkers, you could cruise much faster and it really would not affect the fuel consumption very much.  I bet you could cruise at 32 with no problems at all.  Is 25 just personal preference?  

Aqua_Aura

Personal preference. Don't really want to run the engine too hard. 

LaRea

Before we went out, my boat had already been in the water over a month.  That's a first.  Not because of COVID ... it's the weather.  Always too cold, too windy or both.  I usually have at least 5-10 hours in my log by May 1st.  

J3ff

have never hit more than 40 in my 270... and that was going WITH the tide and wind! normal cruise is 27... can do 34 without too much strain. but after that it's pushing it too hard. 

Ian

My mechanic had our 310 with 2 5.0MPI’s and B3’s up over 40 and me nearly there with all the canvas up still.

Ian

LaRea said:

If your boat is like most Rinkers, you could cruise much faster and it really would not affect the fuel consumption very much.  I bet you could cruise at 32 with no problems at all.  Is 25 just personal preference?  

Via VVM I did some checks last year and burn definitely went up. I can’t recall the math now but while burn increased and tank range decreased, travel time was a bigger change that made it more sense to burn more at the higher rate. I’ll heck this out more this year - if they open the f*&&^g canal...

LaRea

No doubt, speed is a little more expensive.  But the difference is usually no more than 10-15%.  If you're a distance cruiser logging 300 hours a year, maybe 10% is a lot.  If you're a weekend boater in an express cruiser trying to get to your favorite spot 10 miles away, go ahead and open her up a bit!  So what if you spend an extra $7 on fuel for the day.  

Ian

Exactly! The Admiral likes the slow cruise but knows I like to open her up and burn off the dust and happy for me to when it’s calm. I’ll often take her for a burn on my own.

Aqua_Aura

We don't generally travel more than 20 miles and the slow cruise is part of the adventure to take in the sights. 

LaRea

Well, you won't get any argument there!  

When I bought my 342, I called Rinker with an engine question.  The receptionist put me on hold ... and Randy Rinker picked up the phone!  I asked him if I should stay below any certain RPM to avoid engine wear.  He said no, I should go whatever speed makes me happy, and the engines would be just fine.  

I do a lot of slow cruising at 1050 RPM ... probably more than most express cruisers.  But when I'm on plane, I tend to go fast!

Ian

Sounds Iike us! (Last sentence)

Aqua_Aura

I guess the rule of thumb is for long cruising try and stay at or below 75% of WOT. For slow cruise I do about 1200-1500. On plane is about 3200 and above and 75% is about 3500. Between 1500 and 3200 it's just dumping fuel on the fire at that point and not really moving much. 

LaRea

Here are the numbers for the 342, which is representative of many sterndrive boats.  The "best cruise" efficiency sweet spot goes from 22 to 35 mph. 

Suppose you need to cover 20 miles.  At 22 mph, you can get there in 55 minutes for $50.  Or go 35 mph and get there 20 minutes sooner ... same $50.  If you want to get there in only 30 minutes at 40 mph, it only costs an extra $10, and it will be a thrilling ride. 

Aqua_Aura

That's a nice graph. I've had to piece it all together with multiple sources to try and figure it out on the 280. I'm.mostly concerned with engine wear though not really the fuel cost. 

I found this for the 290 with a Merc 8.2 which is probably close to an Volvo 8.1. 

LaRea

Now that's odd.  The MPG peaks at 38 MPH, and it's 25% better than when barely planing.  

Aqua_Aura

Yeah these numbers seem a little different then what I have seen or calculated. MPG below 1500 rpm I have seen to be closer to 2 nmpg and I'm faster at 3500 rpm. My gph seems to be a little less above 3000 then what they get.

LaRea

Here's an interesting chart, again for the 342.  Engine wear is based on how many times you spin the crankshaft (among other things).  I calculated "revolutions per mile" for the 342.  The faster you go, the less wear you put on the engine.  

By going 35 mph instead of 22 mph, it decreases the revs per mile by 19%.  By my twisted logic, if a 342 owner drives slower than 35 mph, that's just irresponsible boating!  

Aqua_Aura

LaRea said:

Here's an interesting chart, again for the 342.  Engine wear is based on how many times you spin the crankshaft (among other things).  I calculated "revolutions per mile" for the 342.  The faster you go, the less wear you put on the engine.  

By going 35 mph instead of 22 mph, it decreases the revs per mile by 19%.  By my twisted logic, if a 342 owner drives slower than 35 mph, that's just irresponsible boating!  

Interesting thought but wouldn't engine load also be an issue not just RPM?