bertram31.com

original 454 setup 17 inch props


new 4LHA-STP setup 21 inch props

Looks sweet!

SS Strut looks pretty beefy compared to original.


Only thing...I'd opt to go with bronze bushings over the nylon.

wonder if ill need longer rudders, the strut plate is 1/2" thick with 3/8 backer on the inside

Great work. I noticed though that it appears the distance from cutlass to prop seems a little large. Maybe it's just the foto.
The thing that 1st caught my eye was the name Amphitrite. Prior to my B33 I had a boat with that name for 15 years. On the radio even the CG would insist on calling us Aphrodite.
Al

its 1.5 inches from prop hub to bearing

Looks great!! So cool getting new stuff! Please pass on how it handles. I've got roughly the same shaft angle as in your picture (19 degrees) and same height in relation to the rudder it looks like. I didn't get to run the boat as much as I would have liked when I bought it and realized very early on that the steering was VERY stiff and rudder control wasn't great. Zero control on one engine. I'm not sure if this was due to the thrust each of these props/engines put out or small rudders being weathervaned into the slipstream!? Differential thrust and you can spin on a dime. I always wondered if it needed bigger rudders and your post reminded me of this issue. If your boat handles like a dream then I'll know I've got some work to do. Could need a bigger steering actuator? Not real sure?

Nice new wheels, definitely going to get more bite.

I am not knowledgeable about inboards so take this for what its worth but it seems to me that there's a big lip where the strut mounts to the boat. Is there any way to round off the metal on the leading edge or put some type of fillet of material in front of it to let water pass that front edge more smoothly? the concept of a fairing block on a thru-hull transducer

KTM....Yes that's on the menu, in fact i'm going to round all the edges and taper what i can. wont happen till end of the season as i'm rushing to get her back in the water. I did the shaft logs per the tips, doubling them up and i'm following the high performance shafting as much as possible.


Ernie....the previous setup she turned on a dime mostly. I have a fairly large double ended steering ram instead of the single with arm, not sure how different it is. My props are also offset to the outside of the rudder just enough that if i needed to remove a shaft i can do it with removing the rudders. Time will tell on how she handles, we still need to drop the engines a touch in the front and when she gets dialed in i will report back.

Got her out finally, 18 knots at 2100 rpm. 290 gallons of fuel, 2 guys and tools. Still need tweak the electronics and next time out we'll run her to 2800 for cruise numbers

19 knots is pretty good at 2100 RPMs with all the weight you are carrying.

290 Gallons is a lot of fuel and weight to carry. Are you using saddle tanks?

Yeah I have 40 gallon saddles.

Saburke17,
Poseidon, god of the seas, had a wife, Amphitrite, mother of Triton.
Tell lobsta1 to tell the coast guard!
Cheers.

yannis, you're absolutely correct. Goddess of the Sea

Boy do we have problems......

So after going through this entire thing i can completely understand now about the importance of shaft angles. My construction brain was thinking about things not backwards but close. here is where i stand now. we got her in the water all set ready to rock and roll with new 21"x24 Teinbridge props. the props guys were going back and forth between 23 and 25 pitch so these props were right in the middle. the mechanic and told me when they were checking the transmission cables for proper direction, they said the boat started to drag the floating dock because of the bite of the props. i was super happy and had positive vibes, we did something right. well that was short lived.....very short. First Sea trial they could only get to 2100 rpms and 19 knots. Took the props off took them to general prop and the guy called me and said the efficiency of the props were too high, about 20% to high. doing the math again we swapped them out to 20"x22 with much lower efficiency. took her out again the rpms raised to 2800 RPM's and then one of the new turbos blew. come to find out the "rebuilt" engine apparently had not been maintained or wasn't rebuilt right because a rusted flake from the exhaust manifold got sucked into the turbo blades and boom. so we dropped a new manifold and rebuilt turbo on. after spending another hour on the phone with the prop guy going over numbers and he still kept saying "sean something is off" we're missing something, props are never this far off. so he swapped the 20 inch wheels for 18x18 and now were at 3000 rpms and 21 knots wide open throttle. at this point i'm completely defeated, second guessing everything so i reach out to a couple guys here, i spoke with the engineer over at Bertram and i went back and looked at the install pictures. We have all come to the same consensus, shaft angle is to steep. with the proper 21 inch prop we are still 2 inches to steep of an angle. we have 6 inches right now between the prop tip and the hull bottom with the 18 inch wheels. Im heading to Fl today to measure the engine angles, then a gallon of gas a flare and my problems are solved.

If your 18" wheel has 6" clearance to the hull - center of prop is 15" away from hull


A rough guess and looking at picture, I come up your shaft angle in and about 15 degrees, that is about right for a large % of the 31"s. 10 degree was for those who had 1:1 gas engine setups with small 15" wheels.

15 degree pushes the water down more, not as efficient as straighter back...WOT RPM should not be effected much by a few degrees of shaft angle. Check the angles and measurements but think you might have to start looking elsewhere. Props, motors...

Sean,
I went thru a bunch of my surveys and found that most of the 31's that are running diesels used 20"x 23P 4 bladed props and the distance between the center of strut barrel and the hull bottom was 15". I hope this helps.
Pete Fallon

With 21" props, I have about 2.5" of clearance, with 1.5" of shaft between the strut and hub.

Whelp, i got my hands on her. And wish i could could get my hands around the mechanics neck. Back story.....one of the engines was fully rebuilt by us, the other has 500 hours on it. when i did the complete rebuild i also had them do the following to the rebuilt one. strip the cooling system off to be boiled out, had the injectors serviced, impeller, oils, filters and all that jazz. I also added a EMU-1 system to convert the analog signals to digital so i could get them on my axiom screens. i took her out Friday and she was definitely struggling, in fact she was pathetic. she was pulling hard to the starboard side so i brought her back in and spent some time and figured out how to get the boost pressure onto the screens. Saturday i took her out again and low and behold..........shit boost. port side has zero boost and the starboard has 17.5 lbs which is why she was pulling to the right. So im guessing the mechanic assumed the turbos were fine since they were new and decided that the issues were the props. so the starboard engine spooled right up when it hit 2400 rpm's like should and she hit over 3300 rpm's.this was in seconds mind you, the port would only go to about 2500 rpms. This has to be the culprit, correct me if i'm wrong. without the turbos creating the extra power the engines couldn't swing the bigger props. if i hit 3300 rpms with 18" props and old half the boost on one engine, in theory with both engines pushing 28 to 30lbs of boost she could swing the 21 inch prop just fine and my performance numbers should be right where they are. At least my Helm looks nice lol

Your helm looks great, hopefully you can get the turbos figured out so you can start enjoying your boat and put that cup holder near the compass to good use.

No boost is a definite problem and would cause a huge lack of power.
You have one motor pulling the other so I'd expect neither to perform or get full WOT, even with the correct props or de-rated props.

If that is all your problems I doubt anyone could tell you from info provided...but get that taken care of and take her for another ride and see.
Surprised the mechanic didn't pickup on a bad turbo...then again its looking at everything at once and assuming certain things are correct so rule them out.

Its a definate could just be the turbo. I have my fingers crossed for you!

And yes, the helm looks Super Sweet...Glad you were able to find a silver lining in that mess.

Saburke, after reading Peter Fallon's post I went out and measured my stuff again. I thought my shaft angles were 19.1 degrees but it was really 14.2. I have the 21" 4 bladed props (21R30). I checked them on Boatdiesel and it says that is the correct setup. The distance from the center of the shaft to the hull was 11.25". Thought you' might want numbers for 21" props as a comparison to another boat. Sounds like according to Peter's post we are in the ballpark. Let me know how that thing handles if you get a chance. Can you steer on one engine!? Mine was like trying to fly a helicopter with no tail rotor.

That helm looks great. Who built it for you?

Sean,
How did you make out after getting the turbo issue straightened out? speeds and RPMS?, the helm pod looks real nice.
Pete Fallon

Finally got a yanmar mechanic recommended and he found a few items that he thinks may be the culprit. He seems confident that its a fuel supply issue and not an actual Turbo one, He found a couple of immediate issues like the port side fuel line wasn't even clamped down tight, the racor filters are 2 micron vs 30, internal fuel filter on port side was never changed. WE have had numerous discussions going over the history and what i saw with my own eyes. He said if i was getting proper fuel delivery and both turbo's were not spooling or "broken" he said i would have a ton of black smoke. At WOT there was barely any smoke so hopefully he is on the right track. We are also going to put the 21 inch props back on to make sure that we can properly load the engines and make sure we have solid boost numbers and then start looking at other things. I'll be in FL thursday and will be running her and will report back.

On the helm guys, I have no idea who built it as it was there when i bought her. Maybe the older guys here who knew the builder who did the re-fit in New York can chime in. the only thing i want to change on it is the angle of the screens, if they were turned at a sharper angle inwards towards the operator they would be perfect. I like to sit closer to the controls so i have to kinda lean over a bit if the sun hits them just right.

The boat was customized by Jim Ray on Long Island-------http://www.jimraymarine.com-----he has done a few over the years.

Just remember when diagnosing turbo issues.
If either the air filter is clogged, engine compartment is not getting enough air flow or the turbo's are not spooling up or rust stuck, your going to be huffing a cloud of black smoke out the exhaust.

A quick update, My mechanic has been out for personal reasons and just got back to the boat last week. He popped the turbos out because he wanted to make sure the aftercooler wasn't plugged Turbo's are being tested and the plugs resealed as they were dripping some antifreeze. He popped the valve cover off and found fresh soot, he also found soot on the intake manifold which he said was really strange since the engine only has about 10 hours on it. Then he checked the clearances on the valves and there was a major problem. The valves were never adjusted after the head was rebuilt, He said they were way off like waaaaaaay off. So hopefully by Wednesday they will be readjusted, tubos put back on and the rebuilt injectors installed, Fingers crossed.

Finally she is alive.... got her out running Friday. 19 knots @2900 rpms. About 3 inches under pitched. Hit 3720 rpms WOT with 285 gallons of fuel, 3 guys, spare props and crap on board. The 18x18 are off any will be moving up in size. This has been a long pain in the ass project and when she jumped on plane a huge smile plastered my face. Still need to fine tune a few more things.

Finally!! Glad you are getting it dialed in. What a relief!

Is this a 31? That's a lot of fuel!

I have to agree with Doug, that is a lot of weight in the stern. Are the exhausts under water?

Yeah its 31, main tank in the middle is 215 gallons. the two saddle tanks are 40 gallons each. the exhaust openings are about 90 % covered as it sits now loaded down

saburke17 wrote:Yeah its 31, main tank in the middle is 215 gallons. the two saddle tanks are 40 gallons each. the exhaust openings are about 90 % covered as it sits now loaded down

As my wife said, these boats are two huge engines and a fuel tank surrounded by a hull.

Amberjack wrote:As my wife said, these boats are two huge engines and a fuel tank surrounded by a hull.

What would be interested in seeing is, at what point do the gallons per hour burned change. If the boat normally holds 220 gallons and you are burning 15 gallons an hour, and cruise of 20 knots, and now you increase the fuel to 290 gallons, how much fuel are you now burning per hour, what is the boat speed at the normal cruise RPM's and at what point does it return to 15 gallons per hour, and normal cruise speed.

There is a trade off on fuel burn and speed, based on the weight of the boat.

But your wife is close to correct.

I plan on spending plenty of time figuring that stuff out. Will be running her up the coast from Fl to Mass in the spring so I'll be able to monitor speed and fuel burn in long spurts

Keep us posted. That could be some really interesting information.

F this thing.........Can i say that?

most recent painful update, So last update when i ran her 45 mins to the new boat yard for some punch list items and then tragedy strikes. They had a few items done and wanted to run her to get some final numbers before they pulled the props. I get a call and the mechanic said he heard a knock develop in the newly rebuilt engine. He sent a video as proof, I dispatched the yanmar mechanic and he confirmed it. short story the engine spun a bearing, and the piston stamped the id number into the head. Took the motor to the yanmar guys shop, dropped the pan and saw chunks of metal and nice pile of metal filings, and the crankshaft was ###### up. it was cheaper to buy a new engine than rebuild, which i unfortunately had no choice at this point. so she's done now, here are the new numbers. The 4 blade props went from 18x18 no cup to 18x20 medium cup #4 i believe. before the max RPMS i hit were 3720. after the adjustment she only dropped 40 rpm's to 3680 to the strb & 3530 to port, the port side is the reverse running transmission so im taking the difference in rpms as the ratio difference. the alignment was double checked, last thing to dbl check is to put a hand tach on the shaft and see if the rpms match the Tach. So my dilemma now is correct sizing of the props, we added basically 3 inches and got almost no change, speed seems to have dropped a hair along with 60 rpm's. i'm disappointed with 18 knot cruise, was hoping for at least 22-23 knots. Can the props be so far off that the 3 inch inch of change was insignificant?

oh yeah, and i need to find a guy by the name of Rocco who can visit this piece of shit mechanic who blew up my engine by doing a shitty rebuild.
https://imgur.com/a/rtOfHSE#dz4Ukmv
https://imgur.com/a/VdF4U1R#2e63Hma

Yanmar 230/240 hp engines. 2:1 gears.

Appropriate wheels are 20X20, 20X21, 21X20 or somewhere in there. If the boat is light, maybe 21X21

Cruise is about 22, top end is about 25, give or take a knot. This is 20 year old science.....

Can you tweak another knot out of it? Sure. But you have an 18 in your equation, you're on the wrong track.

What yanmar are you running, 4lha?

What reduction did you wind up going with?



Why 4 blade wheels if your looking for top end.

4lha-stp

Not looking for top end just high cruise

I'm hitting 25 knots top end already

2:1 zf63a

With so much reduction why are you running such small diameter wheels?
Didn't you have 20 or 21" wheels with a real high pitch ?

Lose a blade and bring the pitch down some so you can spin them up to WOT +


With small diameter wheels you have more slippage, the 4th blade helps...but its also another blade in the water, more drag. I like 4 blade as they are smoother...but 2:1 is turning real slow so smoothness isn't much of a factor. The other reason for an extra blade is to handle additional power...you don't have that much power to worry about over taxing a 3 blade wheel. A 4 blade will also raise the stern abit. Nice to lift the arse with so much fuel at slow speeds, but not really needed going past that just on plane speed with a 31.

I'm not a prop guy...but maybe talk with a good one.




To answer your question on is 3" of pitch a big difference.

Skip the slip and Play with the math...1" of pitch means with every rotation of the propeller the boat moves forward 1".

5280' in a mile and 63,360" in a mile

A 1:1 trans with motor spinning 3000rpm has boat moving 3000" in a minute x 60 minutes in an hour 180,000"

now divide that by 12 for feet = 15,000'

divide that by 5280' in a mile is 2.84 miles per hour.


Your running 2:1 so shaft speed is half that- is 1.42 miles per hour per inch of pitch

So 3 inches of pitch is 3 times that or 4.26 miles per hour running at 3000 rpm for you....theoretically and if my math is right.



Slippage tends to fall in the 10-20% range...smaller wheels more slippage.


18 pitch should be 18 x 1.42 or 25.56 mph at 3000rpm -20% brings you down to 20mph 17 knts?

Ballpark
If I'm off I don't think its that much.

Carl are you a machinist by chance? Nice math!! You are very close, im running 20 degrees of pitch vs 18 but again you're very close.

short answer on the props, the morons doing the repower thought the props were the issue when in fact it was a turbo issue. The figured since the Turbos were new the problem had to lie somewhere else, I originally bought 20x20 and they had them adjusted down to 20x18. they saw their performance numbers come up, so they ended up trading the 20x20 for the 18x18. After i fired them, i got the engines straightened out and now were severely under propped.

I have a set of 21 x 24 Teinbridges that "per the calculator" is supposed to be very close. They are being installed now and i'll report back with new numbers. I didn't stop to think about the slippage part and the effect it would have. So a 20x20 4 blade would react fairly close to a 18x18 because the slippage is less? In this particular situation.

saburke17 wrote: So a 20x20 4 blade would react fairly close to a 18x18 because the slippage is less? In this particular situation.

In a word, no.



Your all over the map...gotta calm down, make small methodical changes unless your way over or under.


Sounds like you were kinda close with 18 x 20

Small wheel slips more, less efficient so I'd be looking for a 20" diameter wheel...
Just keeping the same 20" pitch and going up 2" in diameter you can expect to loose about 400-600rpm at WOT.
What is your rated WOT?


21 x 24" I can't see that doing anything but overtaxing your motors...a sure way to kill them quick.




FYI- propellers don't come in degrees.

A 20 x 20 wheel has a diameter of 20" and the "pitch" is "20" ( meaning one rotation the prop moves forward 20")

A 20 x 18 wheel is 20" in diameter and each rotation should move it forward 20"

Think of pitch like threads on a screw ( twin screw, single screw ). Fine thread is less pitch and a course thread has more pitch.




A machinist- yes

Do not use a 20X24 blade.

Please refer to my post above. I have the same boat, the same engines, the same transmissions, and I've tried a dozen different wheels over the last 20 years. I know what works and what doesn't.......

mike ohlstein wrote:Do not use a 20X24 blade.

Please refer to my post above. I have the same boat, the same engines, the same transmissions, and I've tried a dozen different wheels over the last 20 years. I know what works and what doesn't.......

Saburke wasn't going 20 x 24, he was going bigger, he was putting back on the 21 x 24 4 blade wheels.
18 x 20 and in the ballpark, then jumping to 21 x 24

...and that is a big reason why I stepped out of the recreational end of the business.




Mike, what is the rated WOT for these motors?

"...and that is a big reason why I stepped out of the recreational end of the business"

Carl, im not a "stupid" boater. I Don't just randomly do things because i think i know better then everyone. Before i even started this repower the first thing i did was have a marine architect do a prop analysis. He came back with a 21x26 4 blade, Then i went to General Propeller and they came back with a 21x22. That's how i originally purchased the 21x24 props, right in the middle. They are only going on now to get some more accurate numbers because it doesn't make sense how i can add 3 inches of pitch to a prop and only drop 40 rpms. I have literally spent hours on the phone with Travis from General propeller crunching numbers, going over stuff trying to figure out why this is reacting the way it is.

Rated WOT per Mastry and 2 yanmar certified mechanics is 3400, prop to 3450. yes i triple checked because my plate also says 3300 rpm's.


I will more than likely end up with 20x20 or something close but forgive me for triple checking everything before i go and buy a 4th set of props. I have read here in numerous threads that our boats are the same but can be different at the same time.