cummins 370

[1962 31]

Look up the 31 Bertram that SB Marine did I think it was shooter they used maybe 1.23 gear and smaller shafts with I think yanmars and small props

[Geebert]

Lol!
I just read your reply, Carl.
Need time to process through the imagery

[Geebert]

Shooter has pockets so thats not a direct comparison of what the water sees as the bottom of the boat, plus I'm not sure i trust the numbers I've seen thrown around regarding shooter. I also get the feeling that member's here cringe anytime that name comes up with speed or efficiency discussions. But i have read about it. Its definitely interesting, but i hesitate to trust that info without some reputable verification, which I've yet to find, and i don't think anyone on here will vouch for him either.

[pschauss]

Now I am going to ask you to think about making the best whirlpool you can in a 4' deep, round pool. best is described as the fastest water in the shortest amount of time.

Your given 2 Big Sumo wrestlers and 2 track runners.
...

Thank you for the physics lesson. You have a serious gift for explaining things.

[Carl]

Years ago the lines were firmly drawn.

A diesel worthy of marine installation was a slow turning heavy mass of iron that produced tremendous torque right from the start of the curve and carried up a bit past midway. Slow turning meant big wheels were needed to push lots of water efficiently.

Gas motors develop their power at higher rpms so they could not turn a larger, more efficient wheel unless they used alot of reduction. But then with so much reduction, the motor cannot turn the prop fast enough to go very fast. So smaller wheels are used, they slip a good amount at lower speeds allowing gas motor to get into its power range.

Move forward some years and we have Diesel motors with less mass tuning higher rpms similar to gas motors and then we have gas motors built with more low end power with fuel-injection and other tricks creating more low end torque. So the Diesel wheels get smaller while the gas wheels get larger creating some overlap or as Robin Thicke says in his song...Blurred lines.

I had thought about going the route Pete took...very impressive numbers.

BUT and for me this was the biggest BUT. BUT there was no way I was going to put so much cash and effort into my 58 year old boat to come away with a gas boat. The boat would perform great, burn would be great but if and when I needed to sell it, it would be sold as a 31 Bertram with gas motors. New gas whatevers or my old 440's the selling price would really be the same as it is dictated by having gas motors.


I kept it really simplistic in my descriptions.


As to the shaft angle debate...not much to debate. The closer the prop direction matches the direction the boat is going the more efficient it will be...all other things being equal. That is gas, diesel, electric, jet drive or paddle wheel. How much it helps to reduce the angle - - I am sure it could be figured out ( a safe bet it has) or one could do an install at 15 degree and then modify to 10 or 11 degrees then run the numbers. For me any improvement was some improvement and that was enough of a reason for me.

[Yannis]

Guys, I always wanted to learn Chinese, I’m glad I can do it right here!

[Tony Meola]

Guys, I always wanted to learn Chinese, I’m glad I can do it right here!

Yannis

Are you saying that this is all Greek to you?

[Yannis]

Yes, but we can’t use the same expression for obvious reasons! So, Chinese is the best alternative. No doubt!

[Geebert]

Carl,
I think we're on the same page as far as choosing diesel over gas engines when the budget allows, for numerous reasons.
The theory i was trying to put forward is that with newer, lightweight, higher rpm diesels, you should be able to match the speed characteristics of gas, with the fuel economy and safety of diesel, through taller gears instead of taller props. I haven't seen anyone go at it from that perspective. Trying to find out why not, or convince someone to try it, and let the class know how it goes .

[bob lico]

yes i have big time but never posted it Geebert.i don't post or share everything because it is not within the scope of most of the members of this forum, i tend to go off on a tangent that others might think should not be posted.( hint) did it with a three speed transmission.

[Carl]

I wrote a long answer...but after reading I think it comes down to "Tried and True" or "Give it a Shot".

Stay within the proven guidelines for known results or....


It's a lot of money, labor and lost boat usage repowering, which path does a person take.



On your give it a try side, we have Bob. I think his setup is along the lines you are asking about. Reduced pitch " low gear" to get around tight areas and dock. Lots of cup to artificially "upshift" to a higher pitch wheel once the boat is up on plane.
Bob results speak for themselves...the issue I find is the prop shop. I doubt many can read what Bob describes and understand it enough to explain to their prop shop and "coach them" to achieve what is needed. Nor would either be able to correctly read the results to dial in.

[bob lico]

thank you carl ,ok here we go just this one time. (Geebert) years back i had a friend with very deep pockets into experimenting with engines ,props drive lines.Soooooo we wanted to build the fastest fishing boat possible to go to Hudson canyon, about 72 miles from Fire Island inlet. we went down to southwest Florida and purchased a 32' Viper Cat very similar to worlds offshore champion Skater cat. our marina had so many Yanmmar engines blow up for one reason or another we had twin 440 big block Yammar diesels put in the boat with exhaust headers and forced air intake and other modifications . a three speed transmission, short shafts, and mercury racing outdrives with external water coolers .fishing rods under the deck in hold downs and fiberglass outriggers out of the rod holder type holder and on the floor in two piece set up.First time out black smoke belching out the exhaust in first gear the second gear it started to clear up as boat went up on plane.engine was struggling with prop load. i started with six blade 34" pitch props for the first run. she ran at 60 mph cruise and 90mph wot. he wanted one hour cruise to canyon at most so i learned quite a bit with trips back and forth to back of prop shop after hours.we experimented for months to get that "fishing boat" to top out a 104mph and 75mph cruise. needless to say you need experience running this speed with just the props in the water .Catamarans have a real danger zone if you stick one of the pickle forks in a wave from incorrect throttle positions while sailing over the waves.i took photos`s off the completed boat and posted it but i be dammed if i can find it.the reason for this post is to illustrate a complete extreme of playing with props, drives and diesel engine placement.needless to say the ultimate performance for a 31 Bertram would be attained with diesels and extreme mercury outdrives.they can take 1000 HP. give you any shaft angle.

[Carl]

Been on this site awhile...never recall hearing about the fast cat or seeing pictures of her. If you ever come across I'd love to see, I don't care about the action shots; the motors and hardware do peek my interest. Curious as to why you didn't go surface drives? Maybe not much of a trolling boat then...

Years ago we got to play with a customers boat who also had deep pockets and wanted the largest and fastest Sportfish so had a 92' Lidia built with twin Detroits 16V92 DDeCs and a pair of Lycoming turbines driving hamilton jet drives. The biggest issue was keeping the gearbox to drive pumps intact trying to push 2500hp through them. Well that was after the exhaust issue...they wanted wet exhaust so it looked like a regular big sportfish but the turbine exhaust warped the valves letting saltwater back to turbines...saltwater and magnesium didn't mix well.

But that is not why I'm bringing that up...the diesels would get the boat up and running at a nice pace then the turbines were cranked up and brought online. As the turbines pushed her faster the pitch of props was mechanically changed to give an additional push. Servogear provided a true variable pitch propeller. From the helm at any speed they could change and tweak the pitch of the 38" wheels from 66" forward to 66" reverse.
That would be something to play with huh??

[bob lico]

carl the Arneson surface drives hang out the transom 6' and the Bravo 5 drives are tried and proven .they are SOP. in offshore APBA boat racing with no problems providing you supply a cooler for the gear head ,nothing elaborate just a ss pipe in the water that feeds cold sea water to the upper gear case.the boat worked fine for a recreation boat with 75 mph cruise but was not good as a fishing boat because even with down shifting gears the engines had wrong prop load and smoke like hell at less than 40mph. i definitely posted this around 2006.the racing cat was red in color. a beautiful boat but what i wanted to teach from this post is prop load versus theory. better said as "hey if my 31 Bertram does 32 knots with 1.53 ratio why can't i put in a 1 to 1 gear ratio trans and do 36 knots wot. JUST does not work that way.

[Carl]

You have a 10 speed bicycle.
When starting out you always need to get over a steep hill...with only one gear choice, which gear do you choose?

The lower the gear, the easier it is to get over the hill, but you lose top end speed while pedaling like crazy.

The higher the gear...the harder you push to get over the hill...if you can make it without killing yourself. Or you get some extra muscle, but when you go you go...

Somewhere in the middle is a gear that lets you get up the hill and hit a decent speed. That is the prop, gear motor combination.



Tried and true...got it on the outdrives. Too bad you couldn't get a gearbox with a lower ratio to get started, or variable pitch props...although I doubt they would be balanced and true enough for the speeds your talking.
I cannot believe I do not recall the cat stories or pictures.

[HydroRacer]

"i don't post or share everything because it is not within the scope of most of the members of this forum,"


Give it a shot bob , I have a Doctorate in Engineering , perhaps you underestimate the capacity of the members here , I also saw a post recently that ended in " Got It ? "  Enough with the condescending attitude , it's getting old .

[bob lico]

definitely not condescending just not in the interest of this forum. i should think 99 point 9 of the members are not the least bit concerned about a Mercury racing Bravo five outdrive. so in all honesty i just wanted to tell some crazy experiments with wild props , drives and multi speed gears to attain these numbers, like i said does not apply to most 31 Bertram owners but Geebert inquired.

[Tony Meola]

Enough with the condescending attitude , it's getting old .

Once you get to know Bob, you will realize he is anything but condescending.

[Carl]

"i don't post or share everything because it is not within the scope of most of the members of this forum,"


Give it a shot bob , I have a Doctorate in Engineering , perhaps you underestimate the capacity of the members here , I also saw a post recently that ended in " Got It ? "  Enough with the condescending attitude , it's getting old .

Hydroracer, as you most definitely must have a grasp on this subject, maybe consider trying to explain the answer to the question at hand instead of attacking the person trying their best to explain and share.
In my book people trying to help get extra passes. People who try to help and do help get even more passes. My dad is very much like Bob in a way...you ask him a question, you get a seemingly unrelated story with him front and center with no beginning and no end followed by a couple more...at the end they can sometimes be tied together for an answer that makes sense. Sometimes not so much and it may take another question or two to pull the missing link that ties them. In any case its always an adventure and always a shot at learning something. Plus any story boat or water-related is enjoyed here. Let some tales fly hydroracer, for one explain the tag and what brings you to our board. Thanks, Carl

[DanielM]

HydroRacer,

Other than some posts on this website I wouldn’t know Bob from Adam, and I‘m sure he’d be hard pressed to pick me out of a crowd.

But I sat at the dinette on his boat Phoenix at the Greenport Rendezvous several years ago and he told me in detail about the wood work on his boat and went through the thought process on his fuel system layout and components because I was about to update the fuel system on my boat.

He was(and is) a competent high energy guy and confident in his opinions, but condescending didn’t even cross my mind.

Bob,

Thanks for the input to the board over the years.

[HydroRacer]

Perhaps boys this is " out of your scope of your understanding " " got it ? " ( recent bob posts ) idk what to tell you , other members of the board have subtly and not so subtly checked bob . Not making waves here but come on .... check his posts, CAP LETTERS AND !!!!!!!!!!! , thats akin to screaming @ someone . I don't care for a big fish in a little pond attitude from anyone , especially a keyboard warrior ( stick to the technicals ) . Check his post about moving 2 fla and the local leo or zoning board pointed him back north after " doing all he can to prevent a condo being built to obscure his view " ect , ect,ect . As far as why i'm here ? Why do you think ? Bertram ?? plus i race Hydroplanes and vintage motorcycles .

This is how boards are destroyed . This is just like the " Sky God " attitudes destroyed the new skydivers coming into the sport . Yeah , i do that also . Remember boys , there is ALWAYS someone faster , bigger, badder ,richer , better looking and has a bigger swing d++ck in the county ( and a bigger boat ) . Never forget that . I had clients w/ 70 + Meter Motor Yachts moored in Monaco , you don't see me rubbing your face in it ?? Now i'm sure you all will be in an uproar about my post . The world will be failing globally shortly & you spend your time defending "bob" , good luck boys .

Go with God,

HydroRacer-

[Greg]

UV had a way with words.
I can only imagine how he would reply to that.....post.

[Carl]

Hydroracer I thank you for trying to do what your trying to do. I fully understand your frustration but I ask you to step back a hair and try to understand Bob is my friend.

[Tony Meola]

Hydro

We are only trying to explain that what you might interpret from the way he posts is not the way Bob is in person. His typing skills or how he explains things may lead you to believe that Bob is bragging, but he is really trying to help. Usually when you press Bob to clarify things, you will realize that he dropped part of the story.

Don't take offense to what we are saying, we really just want everyone to get along, and we usually try and avoid personal attacks. Sure from time to time someone takes one of us on, but usually we all walk away shaking hands and putting it behind us.

Given your back ground we are sure you will be a great asset to the site, so don't pack your bags and leave over our trying to explain to you what we have all found Bob to like in person.

[DanielM]

Hydroracer,

Sorry if I hit a nerve, was not my intent, just offering my thoughts. You make a point, and we can all use a little redirection on occasion. Even though this is the ‘mean team’ it’s usually a pretty civil place.

Like you mentioned, there are bigger worries in the world and this is just a small sliver of that world. Don’t let it get your blood pressure up.

I agree with Tony, don’t take offense. Join in the conversation and if I can help with a question I have a background in I’ll give it a shot. Best wishes.

[mike ohlstein]

Come November 25, this board will be live for 21 years.

Over such a long period of time, lots of things happen. Friendships form. People with common interests start to have adventures with one another. People who met on this board (our version of internet dating) have traveled the world together, fishing and hunting and generally making merry. Occasionally, some pass on. We come from all sort of backgrounds. Plenty of racers (land and sea), engineers, doctors, lawyers, artists. Some are world famous, other less so.

There are a load of extremely talented and extremely bright people associated with this place. Some post more than others. Some are more eloquent than others. Some lurk more than post.

The nice part of having a forum like this as opposed to the Facebook group…. is the searchable threads and topics which are never deleted. There is a wealth of knowledge on tap here. Some of it is part of the legacy of members who have passed on. Some is real time current information and hands on help from the type of people who don’t think twice before offering to do you a favor. In fact, they offer before you have a chance to ask.

It’s a beautiful thing.

Twenty one years, and we’ve never charged admission. We never even actively ask for donations. We don’t ask for a piece of the action on the For Sale page. We simply put it out there because it’s what we do.

What we don’t do….. is stand for personal attacks. We try to stress that without being overbearing, but the bottom line is that this is a nice place, full of nice folks. We understand that sometimes people disagree, and that sometimes those disagreements can be heated. As long as those differences of opinion are handled in a respectful way, it’s all good. The moment things take a turn for shady side of the street, it’s over. One warning….. maybe…. then you’re done.

So check your ego at the door and come on in. Show how great you are by helping others. Show how smart you are by helping others. Show how generous you are by helping others.

Be civil or be gone.

Rant over.

[Carl]

Mike, you can hand in your Mean Team membership card at the door on the way out...

[bob lico]

hydro racer ,just for the record i have over 50 relatives in Florida.the protest in Florida had nothing to do with my view, of the ocean i live 5 miles away it was building world trade center type buildings on the ocean of a previously unmolested natural beach on Hutchinson island south of Jenson beach. What a shame for the people of Martin county.

[jrmoro]

All, my name is JR Moro. I have a 1969 FB out of Monmouth Beach, NJ. I am more of a lurker than poster. I have a questions about Cummins & since this thread started out about that & the people who would problem answer are on this i figured i would ask. Is there a reason all the Cummin's repowers seem to be the 6BTA series & not the QSB series?

[Amberjack]

Thanks Mike, that was well said and appropriate. Perhaps we can get you to talk with our national politicians of both parties as well. They seem most interested in driving we the people apart when in fact I'm convinced we have much more in common.

[Carl]

All, my name is JR Moro. I have a 1969 FB out of Monmouth Beach, NJ. I am more of a lurker than poster. I have a questions about Cummins & since this thread started out about that & the people who would problem answer are on this i figured i would ask. Is there a reason all the Cummin's repowers seem to be the 6BTA series & not the QSB series?

I cannot speak for anyone but myself. The idea of less electronics on a boat motor the better. That is what drew me to the 6bt's and 6bta's, the idea of them being mechanical makes me think if something did go wrong I have a shot at fixing it. A computer goes, its pull over to the side of the road and call Triple A. Oh that right...can't do that on a boat.
Then comes lots of these motors went in before the QSB's and then comes the elephant in the room....price.

If I was looking for a cleaner burning motor, a bit more efficient and had more money in my pocket I would not rule out a QSB. I'd still go that route with heavy slow churning iron over Yanmar.

...and welcome aboard, glad you stopped lurking and dove in.

Carl

[Tony Meola]

JR

As Carl said I think it is more about price and timing than anything else. As mechanical engines get harder to find and the price point stsrts to balance out you will see more electronic common rail engines being used for repowers.

I believe you can now purchase Recon QSB engines. So it will not be long before we see a shift in choices.

[bob lico]

this is my experience with the cummins Remans; i purchase two 330hp remans in may of 2006 and wanted to do modifications while in the crates like move the engine fume removal port to the front from the timing gear cover due to nose up installation you want to take advantage of removing all the fumes thru the most forward spot on the engine this being the gear case cover.this was the latest and greatest storm block (same as QSB ) models i examine the engines check the build date of the block -------wtf-----build date was march 2006 well unless somebody purchase a pair of diesels then put 20,000 hours in a month we have something screwy . I spoke with tony aathens at seaboard marine and his words were (shaaa) yes i know the remans are not remanufacture they are in fact brand new but run the fuel injection pump thru the assembly line twice. i am a stock holder in Cummins (CMI) so i inquired . in so many words " due to the two year warranty to the public we felt it best to just produce brand new mechanical engine for repower only that did not have to be EPA compliant,so you are purchasing brand new labeled remans. remans are placed on Dyno for 30 minutes and 4 page composite test report signed by technician is given with each "remanufacture "engine.i just want to add i had the opportunity to examine at least 6 more remans of 6BTA-M3 and 6CTA-M3 and recently QSM-11 all were in fact brand new under the label remans.

[JohnV8r]

Bob,

So sorry to hear about your wife. Our thoughts and prayers are with you.

JohnV8r

[bob lico]

thank you

[Bruce]

All, my name is JR Moro. I have a 1969 FB out of Monmouth Beach, NJ. I am more of a lurker than poster. I have a questions about Cummins & since this thread started out about that & the people who would problem answer are on this i figured i would ask. Is there a reason all the Cummin's repowers seem to be the 6BTA series & not the QSB series?

Mainly because the 6bt series is more affordable than the QSB. Out of all the repowers I did on mid 30' boats I did with Cummins, only one, a 31 was with the QSB and that was when they first came out...way back.

The other issue is 6BT series is mechanical and easy for the novice mechanic to work on. The QSB is electronic common rail. Most novice mechanics can't service them.

I recently found a bunch pics from that qsb repower. Glendenning came with a not sure it would work electronic sync to work with the electronic controls and I have forgotten the nightmare of wiring and getting all those systems to communicate. That and the electronic screens for engine data were the Mercruiser and frankly ugly.

I'm sure it's changed by now.