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What kind of speed can you expect on a Bertram 31 with the 210 Cummins?

Cruise at 20 or 21. Top out at 23 or so?

Very easy on the fuel with those engines.

If your looking for speed, 210's may not be your ticket.

I am installing them in my boat, a nice 20 knot cruise is what I am preparing myself for.
Hoping to tweak the wheels a bit after a shakedown season. If I can keep boat light and clean I have my eyes set on a 21-22 knot cruise.
If it goes that way, I'd happier than a pig in Sh$t. If not, 20 knots is plenty fine with me...I've grown to enjoy the ride almost as much as the destination.

So if I have my sights set on 21-22 why go 210's, that is easy to answer, it's about longevity, choices and being optimal.
It allows me to go 22, 21 as well as 20 without overtaxing motors, I like having that choice. Longevity, if I can cruise 22 as my high cruise, I can cut back a bit on the throttles for a 20 knot cruise and motors work a little easier with a little less burn. Optimal...If you tell me 20 is the best, I want 21. If you tell me the best economy I can expect is 16gph at cruise, I want 15. A lot of extra work went into squeezing out some extra push...

I'm not really a speed person but I want to cruise at 20. I was asking because I owned a 33 Bertram with 330 Cummins. Great engines, never gave me any trouble. Because the aftercoolers were salt water cooled, I was told that they needed servicing every 2 years and that got old.

I'm looking for a Sportfish with lower controls or possibly a Bahia Mar that cruises at 20. Gas is fine. Because I want sometime simple, no generator, no A/C a basic 31. If it ends up a Bahia Mar a half tower or hard top would be great. I was asking about the 210 because I thought I had found one , turns out I didn't. If I bought a diesel boat I prefer Cummins because I have a great mechanic.I like the 210 because it doesn't have aftercoolers and that's one thing less to work on. Hopefully simple=less work=more fun.

I HAVE 210S CRUISE 20 KNOTS AT 2200 RPM AT 2400 I GOT 22 KNOTS AND WOT IS 25 AND ITS LIKE A HYBRID ON FUEL

Tom-

Those would be perfect numbers for me, pretty much what Captain Walter had said he ran, thought you were right in there too.
Capy had the DD, 6-53's at 215hp each but heavy heavy iron @ 15 or 1600 lbs each and he ran a solid 22knts.
3208 natural Cats, I think they tip the scales at 1800lbs each with only 210 hp, running the 31 like a bulldozer at 20knts through anything you point the boat at.

Then I'm told over and over it's 20 knot cruise motors in a 31 with those motors. So ok I'd be more than happy with that.
Give me longevity, 20 knots and let me pass the fuel dock a couple times without needing to get fuel and we have a happy camper right here.

What wheels are you turning?
I'm figuring 3 blade 20 x 21 with a good amount of cup is where I'll want to be.

I have 20" square, 4 blades on now. So I expect to be underpropped a good bit. As I had them sitting in the basement, they seemed like the perfect starting place.

There is a sweet 31 Bahia mar on facebook. Bertram yacht owners site. Tower. 330 Cummins. Looks real nice. Eric Strakos is the owners name. Looks like its in Texas.

Boat’s name is Grass Monkey

While I owned a 33 Bertram with 330 Cummins and they were trouble free, I got tired of cleaning aftercoolers every 2 years. That's why I'm interested in gas engines or 210 Cummins. Less stuff = less maintenance= more fun.

CARL IM RUNNING 20X22 3 BLADE WITH CUP I SENT MINE OUT TO GET 2 MORE INCHES OF PITCH I SHOULD BE A GOOD BIT LIGHTER WITH A FULL COMPOSITE INTERIOR NOW SO I WILL SEE HOW THEY WORK IN A FEW WEEKS

For comparison i am not cummins powered but with 6LP 315hp yanmar. I generally cruise at 26-2700 rpms and 23- 24 mph by the gps in no current or wind. i know i should run higher rpms but wife is most comfortable there. I burn 10gallons per hour total . Bottom is always clean as boat is kept on a lift. 2to1 trans and 1 1/2 shaft with the props 19x22.75 4 blade(tweaked by Wildcat in Norfolk Va) bottom paint is Pettit (Vivid colors). Have never run for prolonged period of time on a trip at 3200 rpm(been told recommended) which gives me about 29-30 mph Hope this helps someone. to me they are very fuel efficient.

ok for the last time; go to custom hose store purchase 6' of red stripe 3/4" id nova flex water hose.next install female hose bib on one end put bare end in 5 gallon bucket and spare bucket filled with fresh water connect to crash valve with main valve off.turn on engine with hose in the filled bucket (engine will suck water more than garden hose can supply that`s why you have 10 gallons ready to go.flush engines every two or three trips. SERVICE INTERCOOLER ONCE IN 14 YEARS , please stop the fake news !!!!!!!!!! like wash women he said she said bulls-it ----330hp cummins or 370hp cummins.use "Salt Away" at the end of each season

Buzz

If you can find a boat with the 250 or 270 Cummins, you will have a fresh water cooled after cooler. Cruise comes up to depending on the dynamics to between 23 to 25 knots. Top end is 29.5 to 30 knots.

I hear what Bob says, but I if you flush the engine after each run, you extend the life of everything, plus if it were me I would add Salt away at each flush.

I only flush at the end of the year, but the while the boat is used in Salt Water, the lagoon I am in is brackish, and actually not very salty.

1962 31 wrote:CARL IM RUNNING 20X22 3 BLADE WITH CUP I SENT MINE OUT TO GET 2 MORE INCHES OF PITCH I SHOULD BE A GOOD BIT LIGHTER WITH A FULL COMPOSITE INTERIOR NOW SO I WILL SEE HOW THEY WORK IN A FEW WEEKS

With your numbers your only getting 13% slippage and that is good news to my ears.
That would put me at just about 21 knots at 2400 with 20" wheels.


2 more inches of pitch...really?? With cup or going to remove?
Wow, 20 x 24 I'd have thought too much for this boat and those motors. Can't wait to hear your numbers.

THESALTYSATO wrote:For comparison i am not cummins powered but with 6LP 315hp yanmar. I generally cruise at 26-2700 rpms and 23- 24 mph by the gps in no current or wind. i know i should run higher rpms but wife is most comfortable there. I burn 10gallons per hour total . Bottom is always clean as boat is kept on a lift. 2to1 trans and 1 1/2 shaft with the props 19x22.75 4 blade(tweaked by Wildcat in Norfolk Va) bottom paint is Pettit (Vivid colors). Have never run for prolonged period of time on a trip at 3200 rpm(been told recommended) which gives me about 29-30 mph Hope this helps someone. to me they are very fuel efficient.

With the same boat and motors I’m doing a solid 7-8kts slower. At 3200 I’m doing about 22kts

Captain Decent
I am mph not knots. Bottom is always clean. the figures are in smooth water and no current environment. Maybe the props or the transmission ratio is different or possibly the bottom paint. I am usually carrying 150-175 gallons of fuel. I am a flybridge cruiser with the added weight of a generator,a/c, 2 4d battery's and a 27 house battery. Will turn 3850 rpm wot and shows 37 mph gps.

Captain Decent wrote: With the same boat and motors I’m doing a solid 7-8kts slower. At 3200 I’m doing about 22kts

22knts is 25.322mph, so your not that far off

Does the 210 have fuel coolers or the only thing it uses to boost it's power is the turbos? I changed the water pumps on my 330's to Tony's Pumps at Seaboard Marine or are the pumps not problematic on the 210 cummins. Are there any weak links in 210's like injector pumps, dropping valves etc.? It seems like the only maintenance is to change the oil, zincs and cooling fluid and keep the heat exchanges clean.

The 210's are super basic with Turbo's only.

Before buying I toyed with the 210 or 250's as being my #1 choice.
I know, I know I had 2 #1 choices...but I'd have happily jumped on 250's too. Having some extra hp is not a bad thing even though one more item to deal with. But a fresh water cooled aftercooler is not a big issue...hardly even an issue.

I'd also have opted for a newer block design and not having a CAV injection pump. But when the deal presented itself, it came as it came and that hit enough of my requirements to move forward.

Simple, efficient, must have parts readily available, long life motors, slow revving mechanical diesel to give me a 20 knot cruise while fitting my budget.

The budget has grown a bit, but not too bad and not sure of the 20 knots just yet...hoping in a few days to find out. But if it does, I hit all my requirements. 20+ knots would just be extra icing on the cake.


-I think the CAV pumps are a bit temperamental to fuel contamination.

-I believe the water pumps may still be problematic, but maybe not. The 210's housings have 1-1/4" inlets for raw water and its 1-1/2" for the larger hp motors...so not the same pumps.

-SB Marine has an idler Pulley upgrade for the idler pulley...the claim is the bolt securing the pulley is too small and breaks. A larger bolt with new bearing spacers to accept larger bolt are being offered for sale. I do not recall anyone having that bolt snapping, but I do know two people who upgraded.