Freshwater frobe

I'm familiar with this hull but just curious if anyone has a good guess on the fast cruise his boat will run at ? ( I know it's not going to be a rocket ship ) the price dropped since it was listed awhile back & I may be interested in this boat ... Thanks in advance if anyone has any info or a knowledgeable guess on the speed with the triple yanmar 350's

jeff32

Many readers but not many posters!

Freshwater frobe

Yup

tommymonza

I will take a stab at it. Triple 350 Yanmars with Bravo's weighs about 700lbs more than a triple Merc package.

65 maybe?

Bob the builder used to have a older Nortec on here with the older 350 yanmars now i think he is running the 420 yanmar which I think might be the 350 wound up but I could be wrong.

some stats on the Yanmar https://www.frenchmarine.com/product...rating-1493-20

A couple threads with yanmars for comparisons this one is trip 315s

http://www.offshoreonly.com/forums/b...r-diesels.html

Also there is a member on here that goes by pstorti that has a twin Yanmar 315 boat

Some good information on this thread also.

http://www.offshoreonly.com/forums/g...ar-diesel.html

Most important thing about them is that they are turning the RPMs they are rated at if not they are over propped and bogging and this will cause blown turbos and bad compression and early failure of the engine. Don't ask me how I know this

bor

iTrader: (1)

I had a 32 whit two cummins Qsd 320 hp very similar engine as the yanmars same displacement and about the same hp .
Mine run 72 mph on the gps whit bravo xr s 1:50 ratio and 34" bravo props .
It take some tab and time to get it on plane as the big props keep the turbo s from spooling up but soon as the come in it will go fast and the mid acceleration is also impressive whit the diesel tq but the bravo don t like the tq
Considering the 40 is much bigger but whit the triple engines I think it s gonna run 65-70 mph as they are fast running hulls .

pstorti

iTrader: (2)

Those engines are 6LY should be 370hp they are larger displacement than the 6LP (315hp) that my boat has. The 6LY became a 440hp motor and currently it is 480HP. So engine wise they should be fine I have had zero problems with my engines, the LY makes more torque than the LP but that boat has been around for a while so it seems like the drives are holding up ok. Have it surveyed and have the engines inspected by somebody who knows what they are doing.

kidturbo

X2 with bor and pstorti...

When it comes to the diesels don't let the HP numbers fool ya. Torque is what moves the boat, and diesels produce higher torque numbers at lower RPM's so the "calculated HP" figures always seem low. A 350hp diesel is producing more torque than a 525hp gas motor. Second factor is gearing and prop selection. This is where the performance builders typically get off track. Ya gotta get that prop speed up where the drive was designed to run, or you end up running much bigger pitch props to compensate and slip values go sky high.

If the builder did the math correctly, you shoud end up with a boat that will run side by side a larger CID gasser, and usually double the cruising range of it...


Only 2 more diesel pro's left here to weigh in, then you've got 99% of the performance diesel boat crowd to answer.

Jupiter Sunsation

BobtheBuilder's current 50 Nortech has triple 480s, his last 50 NT was a triple 850 (gas) boat.

tommymonza

I had a single 6LP300 when they 1st came out . It made it to about 1500 hours before it was so tired it would barely get the boat up on plane anymore
. Engine spec on it was 3600 to 3800. I was running 3600 with a load and burned thru 2 Turbos and one exhaust manifold before Mastery said its over propped turn it to 3800., Too late the damage had been done and the motor
had been lugged to death already and had bad compression. This was back in 1998 when the 300 ist came out.

Replacement for the 6LP300 was the 6LP315 in about 2002.

The specs on that motor which was the exact same motor as the 300 was now 3800 to 4200rpms

They decided the motor needed to breathe a little better now. Soon after they dropped the 6LP315 from the line.

Great little motor I read the Aussies have them in their Landrovers over there. I was told it was a oriiginally desighned to go in light Toyota Excavators. The motor says Toyota all over it

Now the 6LY series is supposed to be a complete design and build by Yanmar not a marinization of production land based motor.

and built much more robust ,hence so much more weight than the lightly built 6LP series/

I think the 350 was soon upped to the 370 and than later to the 420 and than to 440.

I think they were all the same displacement but I could ce wrong

Anyways long story short make sure the boat is turning the spec RPMs and not even a 100 under or it is being slowly killed.

The Bravos would be the one thing I would be worried about with all that torque if someone wasn't easy on the throttles, which would be hard to resist with all the torque coming on hard once the turbos are wound up.

tommymonza

Your right