RPMs and planing speed on 312
rinker312
Member Posts: 255 ✭✭
All. I was just wondering what others with a similar boat to mine are able to plane at as far as mph and what rpm they are at to get that speed.
My boat gets up on plane pretty fast no issues there. Unless I am really loaded down.
I usually cruise between 25 and 30 mph on my gps at 3800 to 4000 rpms. Is that about normal for my boat? I can slow it down but I have to lower my tabs and trim to try to keep it on plane and the engine just sounds like it is struggling.
Just want to see if this is normal compared to others. All my boat details are in my signature
Thanks
2004 Rinker 312, 5.0 Merc's, Bravo III, Lake Wheeler, AL
Comments
r312, what you are seeing is what I typically had with my 310. I think I may have gotten about 28-33 in the range you are talking, but I also didn't have any bottom paint. I also had the 5.0 MPIs with B-III.
I'll say I had smartcraft connected and fuel burn was usually best at the higher speed (~31-33mph).
Dream 'Inn III -- 2008 400 Express
Ok just wanted to be sure I was in the right range. I would love to do smartcraft but just can't bring myself to spend the money on it.
2004 Rinker 312, 5.0 Merc's, Bravo III, Lake Wheeler, AL
I cruise at about 38 mph, at about 4200 rpms. Two adults, 4 kids, & dinghy on the swim platform.
That's impressive. At 3800rpm I'm upper 20's for cruise. 2003 342.
PC BYC, Holland, MI
BD that sounds a little slow. I do about 30/31 at that RPM
Raybo...I agree..plus my gph seems high to me too at 30-32gph. What prop pitch are you running? I switched over to a 22P from a 24P several years ago (Bravo III)...the boat with 4 adults would barely and sometimes never get on plane...and sometimes take MILES to get on plane and loaded up the engines bad... add a few more kids and forget about going on plane. I run pretty light with gear on board too, so it's not Iike I have a lot of crap on board. lol
I can't believe bottom paint kills it that much (Interlux Micron CSC), lots of boats use that stuff by me.
PC BYC, Holland, MI
Last year I was having problems getting on plane or staying on plane, thought it was my weight, as we have a big family and lots of gear including a dinghy, had no motor issues or alarms.
Ended up being the anti-siphon valve on the port tank was restricting the flow.
on my 310 with 5.0 BIIIs, I get 32 mph at 4000 rpms per my GPS. seems like you are right in the ball park.
Good to know I am in the right range. Saltwater is more buoyant so I bet that you can get a little more speed on the salt.
Weber. What engine drive combo do you have. Seems like you are really going. I seldom go WOT but I probably can't get much more than that wide open.
2004 Rinker 312, 5.0 Merc's, Bravo III, Lake Wheeler, AL
r312, you should be able to hit 40mph without issues. I had the same setup as you and would top around 43mph at 4800rpm.
Dream 'Inn III -- 2008 400 Express
My 2003 290 with twin 4.3 bravo3 drives does 32 at 4000 and 43 at 4800 that's full of fuel and water tank full and four adults
As a general rule, ideal cruising speed on plane is reached at approximately 75% of maximal RPM. It all depends on conditions on the water...
I am able to keep my boat on plane at a minimum of speed at just under 3000 RPM, but if I cross a wake from another boat, I will fall off and will need to push the throttle...my best cruising speed is about 25-26 mph running at 34-3600 RPM.
I can go faster, but my fuel consumption and economy do suffer....
Don't get the smartcraft....you will become obsessed with the numbers and won't enjoy the boating as much...I still have obsession with the ideal RPM for the best GPH and MPG...
I found that conditions on the water have immense influence on the numbers...I am trying to wean from it all...
Very interesting discussion. My tech told me they had gotten 46mph at 4600rpm during the Axius set-up and I kinda doubted it but - he was right - my EC 360 with twin 8.2 mags Blll X drives with SS XR props - is getting 34mph at 3400 rpm, 38 mph at 3800 rpm, 40 mph at 4000 rpm, 46 mph at 4600 rpm 48mph at 4800 rpm.....and if I play with the trim a bit at wot even with about 70% water/gas/waste I can hit 50 - smart craft so it's all on the gps. Guess I outta be happy. With the 8.2s there are no torque issues. Full load and 6 adults and it rips onto plane- of course all this as the gas tanks run dry - but as thrfxr says, don't watch the guages. He's right, of course...... but I DO watch the gas gauge, only I really don't care. It's just too much fun. MT
I do agree, my main reason for Smartcraft is to tell me when I need to add fuel (much more accurately than gauges. Also, if I get an alarm, in plain english I know what it is. Nothing better than that if you are out on a long trip and at least now what the issue is.
Dream 'Inn III -- 2008 400 Express
I have twin 350 mercs with bravo III's. Don't remember what props.
Weber & Rinker 312 - for what it may be worth, I just went to my stats binder and looked at the stats for our 2013 Rinker EC 310 with T-350 mags and B llls with ss props. I believe the 310 and the FV312 are pretty similar in weight both being right about 12K pounds. I think the FV 312 was listed at 11 feet+ beam and the EC 310 is listed at 10 feet+ beam. I believe the FV 312 is slightly longer by 8-12". My final stats for rpm/mph/gph for a 90% "wet" boat were: 3300rpm/25mph/22gph 3400rpm/27mph/22.7gph 3500rpm/28.5mph/23.7gph 3600rpm/29.7mph/24.6gph. No bottom coat. Temp about 80 degress, rel.hum. about 70%. This was according to my Smart Craft gauges. MT.
This is from this weekend.
Cruising along pretty good Weber! Were you hurrying to get the Rinker Rendezvous??
Missed you there, hoping you would show up with the whole family (had about a dozen kids together) What's your top speed?
Dream 'Inn III -- 2008 400 Express
We had plans with another group that conflicted with the Rendezvous, hopefully next year we can make it.
With the boat weighted down and the dinghy on the back we max out at about 43-45mph at 5,000 rpm on calm seas. Sea trial with empty boat, tanks half full no water or sewage we hit 52mph at 5,000 rpm.