3208T CAT's; 1W5900 Arrangment

photo finish · Post by **photo finish** » Fri Mar 18, 2005 4:21 pm

stu, i will have to look up my estimate to be sure but i think the new shafts were estimated around $1200 each i think they are reusing the coupler they are putting on dripless shaft packing at a cost of $350 each and new cutlass bearings are $100 each so i guess that is about $3300 for shafts, packing boxes and bearings ...i guess i dont really know what the hub is...is that the part that goes through the hull that the stuffing box attatches to? if so i dont think they needed to replace those...they did however take the struts off and reattatched them with the new bearings in place....no precautions on the new shafts since my engines were slid back i wanted to use my existing shafts to save $2400 but they strongly suggested that i put new temet25 shafts on since my aquamet22 shafts were 24 years old .my old shafts are in pretty good shape but i decided to go with their recomendation...i guess their engineer that advidsed them said that is the way to go. i think i would have been comfortable with my existing aquamet22 shafts, to think most of our boats have the original shafts and i have only read one snapped in all of the forums i have read...not too bad there are alot of factors that can cause a shaft to snap without it being the fact that the diameter is an 1/8"smaller.anyway i am no expert just a logistics freak....i hope this babble helps....also my cousin is a metals dealer and he said if nothing else the temet 25 is extremely corrosion resistant. Tim Stamm Photo Finish 1981 33' Bertram FBC

banispeter · Post by **banispeter** » Thu Mar 24, 2005 2:52 pm

Well. Here is what I have found out. Bertram put me in touch with a company in Hollywood Florida that specializes in 80's or so Betram repowers. It is run by a guy name of Jo Jaeger. It is my understanding he was the propulsion engineer for them back then. Among the things he said, these comments are the most salient. 1. The 270 HP versions of the 3208t's were rated at 2400 rpm. Hi idle no load was in the 2800 rpm range. 2. The 320 HP versions are rated at 2800 rpm. Hi idle no load was 3200 rpm. 3. My engines hi idle no load at 3200. He said that is all he had to know - I have 320's. 4. He said 20x23x3 or 20x24x3 NIBRAL, #5 cup is a good propeller for the 320 HP. 5. He said 20x24x3 or 21x23x3 isa good propeller for the 270 HP. He said the same transmission but 200 less propeller speed. 6. He said Acumet 22 shafts are required for the cats. Anything less and I will be snapping shafts. He sent me a couple of pdf files showing acumet 22 shaft safety ratings for the 320 hp with various gears and shaft sizes. He suggested going to the 1 1/2" shaft and recalled the struts that came with the 1 /3/8 would work without difficulty. I checked that out with Danny Piedras of Hightide marine and he agreed but suggested changing the struts to bigger ones for safety. So, what the blank does all of this mean I wonder?

banispeter · Post by **banispeter** » Thu Mar 24, 2005 2:55 pm

Oh yes. One more thing. I learned the 502 gears will take up to a 1 1/2" ahaft so changing out from the 1 3/8 does not require a gear change and immediate poverty. But then again, think IRS would mind if I took a year off come April????

franklyprice · Post by **franklyprice** » Thu Mar 24, 2005 3:41 pm

Peter , I find this interesting. It doesn't sound as though you really need to do anything, do you?I don't recall you mentioning what speed you cruise and top out at?I assume by the numbers and all that you're cruise is at least 23 or 24 knots? If so, and since you reach the 2800 rpm top, it sounds like it's all good, yes? I mean, I think I'd like to have your problem....[:D] Am I missing something? Frank Price

photo finish · Post by **photo finish** » Thu Mar 24, 2005 5:03 pm

Mike, i am sorry i called you stu in an earlier post for some reason...you asked about the cost of the shafts i found my estimate and i was quoted $1000 each for shafts when i thought i was going with 1.5" shafts since i went with 1.375" shafts i think they will be less than $600 each.the price should be less also since my shafts will be less than 7' instaed of more than 7' they seem to price them by the foot Tim Stamm Photo Finish 1981 33' Bertram FBC

banispeter · Post by **banispeter** » Thu Mar 24, 2005 5:07 pm

Frank: No, the current props are 20x22 no cup so I am topping out at 20 knots. Also, I am a little heavy. So I think it's the 1 1/2 shafts and the bigger props. Would love to do 25 knots.

photo finish · Post by **photo finish** » Thu Mar 24, 2005 5:24 pm

I agree with frank. it sounds like you are getting the max out of your engines with the setup that you have.what is your wot speed? it sounds like performance is what you want to increase and changing struts and shafts isnt going to help there, of a matter of fact beefier struts and shafts will add alot of weight to the boat... it was also nice to hear that danny from high tide agreed that in his oppinion that if you are going to increase the diameter of the shaft then you should get heavy duty struts however i would still like to know how many of you have ever had your aquamet 22 1.375" shafts snapped everyone seems concerned about this yet i have still only heard about the one on this site. Tim Stamm Photo Finish 1981 33' Bertram FBC

photo finish · Post by **photo finish** » Thu Mar 24, 2005 5:29 pm

peter, if your rpm rating is where it needs to be how is changing props and shafts going to increase speed? Tim Stamm Photo Finish 1981 33' Bertram FBC

franklyprice · Post by **franklyprice** » Fri Mar 25, 2005 12:35 am

Peter , Tim says what I'm trying to say I guess. I'd look at ways to clean up your running surfaces , how's the bottom look? Have you had your props scanned? If your engines are turning to the rated RPM, there just isn't going to be much more with a different setup , maybe a little difference and maybe a little safety factor with bigger shafts, but I would be surprised to see more speed by changing anything other than increasing HP or cleaning up the running surfaces. It would also be interesting to see what your fuel burn is at cruise , as kind of a diagnostic tool to see if the engines are in fact pulling too much load at a given RPM. Flo-scans are a good thing. Frank Price

banispeter · Post by **banispeter** » Fri Mar 25, 2005 2:30 am

Both Danny and Jo Jaeger said the props are too small and not producing enough thrust at the prop. They can take much more prop. I wish I could figure out how to post all of their email to me.

banispeter · Post by **banispeter** » Fri Mar 25, 2005 2:41 am

This is the first email reponse I had from Jaeger. Peter, Interesting case. Lets start with believing that the CAT statement is correct. That means that A) the MG502-1 is overloaded [see attachment MG502-1, Twin Disc selection Guide October 1996] B) the propeller shaft size is too small [see attachment shaft calculation] C) the 20x22x3 propeller does not load the engine to 320 HP [that explains why your engines turning up to 2800 rpm too fast <by the way, what is the max rpm under load WOT?] Now if the propeller would be loading the engines to 320 HP, the transmission would fail and the propeller shaft will break - it would be only a question of time. Since the propeller is to small and not loading the engines to capacity the system is obviously within their designed capacity. You got two options here: Â· Accept the boat performance as is and enjoy the additional safety margin in your engines. Advantage is longer lifetime of the engine and you are not burning the fuel for 320 HP — about 10 GPH more for both engines. However the 1 3/8â€� shaft size is marginal and if you go off-shore fishing, upgrading the shafts to 1 Â½â€� AQ 22 is recommended. Â· Use the 320 HP and replace the transmission and propeller shafts. There are two possible scenarios. o MG5055A, 1.53:1 reduction and 1 Â½â€� shaft. New shaft seals, recommend TIDES MARINE. It could be possible that you can replace the shaft bearing in the struts, or bore them for the new 1 Â½â€� shaft. This needs further investigation. Propeller size 20x23x3, NIBRAL, DJX [new style Michigan wheel] or add pitch to the existing propellers with 0.075â€� cup. This is the low cost version o MG5050A, 1.8:1 redcution, 1 Â¾â€� AQ 22 propeller shaft, new shaft seals, most likely new struts and propeller 21x27x3 ACME, 0.75DAR, 0.045â€� cup part # 792 & 793. This would be the ultimate technical solution to use the engines to capacity and improve boat performance. Let me know how you want to proceed. Best regards, Jo Jaeger JTC Technical Consulting Hollywood, FL Voice: 954-929-1333 Fax: 954-926-5195

banispeter · Post by **banispeter** » Fri Mar 25, 2005 2:44 am

This was next. Peter, I agree with your boat broker. However, upgrading the transmission, shaft and propeller is not a true re-power. I do know that boat’s like yours in good shape with complete re-powered propulsion systems [engines included] do sell very well. We predict: Â· 27.0 knots @ 2880 rpm Â· 24.8 knots @ 2600 rpm Â· 22.6 knots @ 2400 rpm at a Â½ full displacement of 24,000 lbs. and 320 HP at the flywheel of the engines. The performance difference between the two options will not be much, but with the 1.8:1 ratio: Â· Propeller efficiency is better Â· Thrust values are higher Â· Propeller tip speed is reduced Â· Propeller blade loading is reduced Now, to make your decision a little bit more spicy, consider a complete re-power. Let’s say brand new TIER 1 [exhaust emission] engines ~370 HP [not necessarily CAT], new transmissions, shaft, strut and propeller. That will cost you about $80,000 for the complete package including labor. Ask your broker what your boat is worth as is and add this to the cost of repowering. Compare that to what someone needs to spend for a new 33 footer in comparable quality like your Bertram. Let me know what you think Best regards, Jo Jaeger JTC Technical Consulting Hollywood, FL Voice: 954-929-1333 Fax: 954-926-5195 -----Original Message----- From: Banispeter@aol.com [mailto:Banispeter@aol.com] Sent: Wednesday, February 09, 2005 9:27 AM To: "Jo Jaeger" Subject: RE: Jo: Sorry for the delay in getting back to you. We do tax law and our flock of accountants drive us nuts with questions at this time of year. Caterpillar has verified that the 3208T's are arranged for 320 HP each. Therefore, I have a question for you. Based upon your experience, what will the boat's performance curve look like under the two options for new gears you have recommended? Caterpillar tells me either option sounds great to them. But, before I pour a small pile of monmey into the boat I want to be able to make an informed decision about what value I will be getting by way of performance. Weighing on my decision is the fact that my favorite boat broker tells me he would be unable to readily sell the boat with performance as it stands now, and, that's a bummer. My kids are getting older and I believe I need more room (I have 4) so I would be looking to increase the saleability substantialy by this upgrade. Please advise. It's starting to get warm up here. It's in the 40's! Thanks again. Peter

banispeter · Post by **banispeter** » Fri Mar 25, 2005 2:47 am

This was the last one. Peter: Three things: A) The 270 Hp versions were rated at 2400 rpm. Hi idle no load would be in the ~2800 rpm [~15% higher than rated] The 320 Hp versions are rated at 2800 rpm. Hi idle no load would be ~3200 rpm You said in your January 18 e-mails your are getting 3200 rpm hi idle no load. That also indicates that your engines are set for 320 HP. 320 HP should get you in the high 25 knots range. Use cupping to increase engine load as necessary 270 Hp will bring you in the 23 knots range. Use cupping to increase engine load as necessary B) See if you can get your brokers friends 21x23x3 and do a sea trial with your boat. These wheels are two inches bigger than yours and should reduce engine rpm by ~75 — 100 rpm minimum. Try to find a set of 20x24x3, NIBRAL, # 5 cup wheels and sea trial Compare sea trial data. C) 20x23x3 or 20x24x3 # 5 cup is a good propeller for the 320 HP 20x24x3 or 21x23x3 is a good propeller for the 270 HP [same transmission ratio but 200 rpm less propeller speed] JJ (Below is what Jo is responding to:) A boat broker I know told me later today that he has a friend with my boat in the same era and it is 270. CAT sent me specs showing it as 312 or so on the static test for that serial # era. Boat broker says Bertram probably changed the fuel rack and injectors to bring it down to 270 and says further that it they were around 320 then with the 20x22 props on there now I found spin way past 2800 and get close to rated no load of 3200. Everyone has an opinion. Can you suggest how I can verify this point? You've probably heard this before but the check is in the mail.

banispeter · Post by **banispeter** » Fri Mar 25, 2005 2:53 am

I can't figure out how to attach the pdf files Jaeger sent to me. I'll ask a techie later in the day.

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