Diesel repower (28 bertram)

Major · Post by **Major** » Jun 30th, '09, 21:25

I have two diesels that my dad bought a good while back that we planned to run in the boat but never really did the repower. One of my issues now is if i take on a repower on my own is where to start? Back when we bought the engines there was an issue with the transmissions. Im not sure if it was the engine angle, the shaft angle or the gear ratio but we didnt see it through. Another issue i do remember i with the gear ratio we may could get away with a 4 bladed prop but a 3 was too large. We also have some bertram 31 rudders that we wre going to use.

So not knowing near what i need to know are there any good books or videos out that could atleast get my feet wet to the process? This is one reason we looked into outboards as an option but i really prefer the look of the inboards.

Thanks,

Major

Buju · Post by **Buju** » Jun 30th, '09, 21:36

Start reading trough the pages of this bulletin board. Many, many threads dealing with the numerous and varied aspects of repowering w/ diesels.

In Memory Walter K · Post by **In Memory Walter K** » Jun 30th, '09, 22:35

Do the transmissions have any name identification or numbers on them? First step to getting to what the ratio is. What kind of diesels/HP? What's presently in the boat that you're going to replace? That's a start for us to get going.

Bruce · Post by **Bruce** » Jul 1st, '09, 05:53

call me at 561-622-1736 after 2 today.

If you can't today tomarrow or the next is okay. Just slammed until 2 today.

I'll go over what you have.

I'll need to know engine make, hp, gear make, model, and ratio. And engine condition, i.e. new, used, running, not running, rusty hulks, etc.

I'll also need to know your current shaft size.

If your not sure of what you have, post some pictures of the engines and gears.

Major · Post by **Major** » Jul 1st, '09, 18:51

Ill try to give you a call tomorrow or friday as long as the offer is still good. Whats a good time to call on either day?

I looked at the engines and transmissions today and while there is some rust they arnt near what i would call rust buckets.

Engines: Cummins 4BT3.9M's rated at 150 HP @2800 RPM. While the engines are used they are very low hours. Back when my dad bought them the story was the marina owner had them in his boat and Catapillar offered him 2 engines to demo so we bought them prom him when he did the swap. I would really like to rig up some kind of test stand to be sure they still work fine though. We were going to have them manually turned by a diesel shop here but didnt for who knows why. The open ports are still taped over and its been covered for part of their sit and under a shelter and covered for say 3 years.
-The boat initially came with 2 351 fords but we removed those a long time ago and they are long gone. The boat yard raised the deck a couple inches to accomidate the engines but i remember them barely hitting the hatches still. They may not have been fully adjusted to their "ride height" though.

Transmission: Hurth HSW 630 A1 - 2.0

Here i have some conflicting info so ill have to recheck it. I thought i read for the A ratio it was 2.04:1 and the B was 2.1:1 but a data sheet i found on it sais the 2.0 has a ratio of 1.93:1 for A and 1.97:1 for B. I dont have the angle for them but they are the angled model.

Shaft Dia: 1.375" I know we had talked about upsizing the shafts so thats probably them. They look too clean to be used shafts. I dont have a length measurment

We dont have a prop yet as we were having issues with that.

Thanks for all the help,

Major

scot · Post by **scot** » Jul 1st, '09, 19:11

First: Talk to Bruce.

Now here's my opinion. The 150HP 4BT's are great engines...are you sure they are not 155HP? They will last forever at that power level. The 250hp 4BTs had MANY injector problems.

The shaft size if fine.

The optimum gear ratio is 1.50:1, in a downangle configuration. The 2.0:1 Hurths "may" work. The prop pitch would be high, and the diameter small...which means that you will not be able to take advantage of the little diesels torque, but it will go throught the water never the less.

The 28's hull has a sharp keel, the 20, 25, 31 Bertrams have a much more rounded keel = the 28's hull design needs more power to plane and maintain a plane. The RHO (Ray Hunt Originals) plane easier and will plane at slower speeds than your hull.

This will be a slow boat. If you can live with that, the engines will give you little or no problems, forever (assuming you maintain them, and they are currently in good order). My raw guess is "like" 17-18kt...20kts+ going downhill with a tail wind. Those speeds don't bother me, but they may get on your nerves?

Do a bit of research and I think you will find that the 155hp 4Bs can be turned up a notch and produce something in the 170hp range, and still be ultra dependable. This would change your speed equation.

As with all things boat, it all depends on "what" YOU want from the boat.

IMHO.

Major · Post by **Major** » Jul 1st, '09, 19:36

Scot: Well that opens my eyes some. I wouldnt mind some upgrades to the engines to add some power but 18 is a little slower than i would prefer.

I really wish we had the yanmars we looked into after we had the cummins. Those basically fixed all the issues but wernt cheap considering we had already bought the two cummins.

I guess if all else fails i can get the hull ready for a repower once a little extra money comes my way.

Ill see what Bruce can come up with and send a small donation to the site for all the help and guidance yall have given me.

Harry Woods · Post by **Harry Woods** » Jul 1st, '09, 20:28

Major,
Before I did my B28/Yanmar repower some years ago, I spoke with a yard located just north of Myrtle Beach. He had done several B28, B31 and B35 repowers all with Cummins. He gave me pricing on the little 4BT,s and assured me that the cruise would be at least 20 knots. The only disadvantages were that my boat is an early model that would require elevating the deck and that the engines had a rough idle at low RPM,s. I have searched everywhere and cannot find the name of the yard. He was wired in with the local Cummins distributer and did testing for them on new models. I am sure they could help you find him. Since your deck is already raised, I would not hesitate to use the engines you have.
Harry

scot · Post by **scot** » Jul 1st, '09, 20:33

Major,

I've been know to be wrong, I only write like I know what I'm talking about.

You may have some one that owned a B28 + 4B 150s chime in and disrespect me in front of the entire world, but I don't think the boat could do much better than 20 esh kts. I think the 2 150s would be a 25kt boat in a B25, in fact just about perfect for that hull (total 1700lbs and 300hp =perfect for a 25). And as I mentioned, that speed would not bother me one bit. Free-is-free, and those engines are yours.

Good luck and remember, Bruce is a professional, I only play one on the internet.

Harry Woods · Post by **Harry Woods** » Jul 1st, '09, 21:37

Major,
The Myrtle Beach facility was Hague Marina (843-293-2141). I stopped there running the ICW and by car to discuss repower. Let's see if the locals have some feedback on him. He may have the answers you are looking for on the the small 4BT,s.
Harry

Major · Post by **Major** » Jul 2nd, '09, 06:22

Actually thats where we bought the engines. We didnt have that great of an experience with him overall for all the work that was done. My dad also told me that Hague marina burned down a while back so im not even sure if it still exists. Things must have been memorable because im terrible with names but i can still remember the marina owners first name.

With that said he was the one that said the engines would work and run in our application just fine. What i remember them talking about was the prop would have to be too big to make it work so 4 blades were discussed the issue is still at hand.

Bruce · Post by **Bruce** » Jul 2nd, '09, 07:46

The only gear box I've used in 28 diesel repowers is the twin disc at 10 degree down angle.

The Hurth has a 8 degree and the only way I've been able to clear the hatches was using the 10 degree.

That was just me in trying to save hatch mods. Don't know what anybody else has used.

Hyena Love · Post by **Hyena Love** » Jul 2nd, '09, 08:44

Relative to gasser, all the oil burners have a rough idle. Damn those Chevy small blocks are smooth.

Running Yanmar 240 (old 230's) in mine, a '72 hull (or is it 73, I forget, early 70's for sure) and I raised the hatches. I'm running twin disks at something like 1.44 to 1 (off the top of my head).

My hatches lacked just a hair of closing. Like 1/2 inch or less. I raised them a good bit so as to make room for serious insulation/sound proofing. Plus, the hatches flex with foot traffic, so if the clearance is real skinny, you might get some rub due to added weight.

One piece of advise - I went to 1.5 inch shafts. Likely over kill in my application, and I'm forced to drop my rudders to change props.

No comment on the Cummins. I was seeking more speed among other things, so while I considered the higher output Cummings 4 holers, the injector problems where a concern.

Hal had a super heavy B28 with Yanmar 170's as I recall. Major tower, genny, and the works. I'm not convinced he ever saw 20 knots. But, that was a real heavy boat.

Eddy G. from round here has a real slick B28 that used to run Yanmar 170's. Perhaps he will chime in on cruise speeds.

Bruce · Post by **Bruce** » Jul 2nd, '09, 09:15

Don't think you'll be able to use 2:1 gear boxes and clear the hull with props without changing shaft angle even with the low HP.

BTW a 28 I did with 170hp(at the owner insistance to save money) would not come up on plane with 4 guys and dive gear. Too much weight.

To me 240hp is the minimum for that boat,

Eddy G · Post by **Eddy G** » Jul 2nd, '09, 11:23

The 170's pushed my B28 18 knots at 2950 rpm with a medium load. Full of fuel (240 gals), water, dinghy, outboard and a weeks worth of stuff, 17 knots. I was running Hurth 630a's at 1.5 to 1, 1-1/4" shafts and 18 x 16 nibrals with a slight cup.

After repower with 240's, 22 knots at 2750 rpm fully loaded. Zf 63a's at 1.5 to 1, 1-3/8" AQ22 shafts and 18 x 18 DJX nibrals with a medium cup.

I ran the boat for seven years with the 170's and was fine with the speed. Now, it would be hard to go back. Boat steers and handles much better at 22 - 25 knots.

Eddy G.

Major · Post by **Major** » Jul 3rd, '09, 08:22

Bruce: Nice talking with you and thanks for the info. Our conversation helped make things clearer than you may know.

Ill go ahead and call my 4BT's underpowered right now. As they sit they are supposed to be 180 hp but thats with injector and pump changes.

How realistic would it be to look into performance mods to the engine? That doesnt seem to be mentioned much on boat forums for some reason unless its a cigarette type boat. I know the Cummins 250 hp version had injector issues but ive seen some aftermarket ones avaliable. That may or may not help the issue but i really dont know what the problem was with the injectors on those. I read on some forums where people were doing conversions for jeeps etc. using the engine and 250hp was considered the top end for reliable for them. There were people with over 500hp but i bet those engines didnt have any life as they were more race engines not to mention fuel guzzlers.

Anyone have any ideas for modifications to think about that wouldnt hurt the reliability of the engines while getting my numbers closer to the 250 mark. I would think that my fuel burn would still be less than gas engines and id have a more stable fuel fire wise too.

Im still trying to track down the part changes that cummins used to create their 250 hp model so i can atleast see whats changed and what i need to find an alternative for.

As for the transmissions Hurth does make a 1.5:1 so if i wanted to deal with the angle i may could regear mine depending on if that was feasable vs a new transmission.

In Memory Walter K · Post by **In Memory Walter K** » Jul 3rd, '09, 09:48

The problem with the Cummins 4 cyl 250 hp engines was injector tips falling into the cylinders. Cummins recognized the failing and made the modifications for the owners and those that had them loved the engines after that. Doc, one of the bretheren used to run his back and forth between New Jersey and Florida and give us stats on performance that were incredible. Maybe he'll chime in. We haven't heard from him for a while. If I am not mistaken, it was a change in injector types that was the solution, but if the issue already happened, then there was internal damage that had to be repaired/replaced. I would check with a Cummins expert (Tony Athens) on what to look for/at on any 250 4cyl Cummins I was looking to buy. As far as "souping up" what you have now, it's usually not as simple as a different injector pump and injectors, both of which can come to a pretty penny. The cost vs performance difference vs it's affect on the life of the basic engine may not be worth it.

Bruce · Post by **Bruce** » Jul 3rd, '09, 16:35

The 250 came with the P7100 pump. If i'm not mistaken the lift pump, injectors, lines, timing case and some other parts need to be changed.
I haven't done much with the 4BT cause I never saw many of them.

The cost for conversion out weights the effort. Besides as most who have spent time with the 4BT 250 will attest, injector issue aside, longevity is not the norm.

First 31 I ever repowered was pulling out a pair of 4BT 250 that were eating the owners wallet on repairs.

Hyena Love · Post by **Hyena Love** » Jul 4th, '09, 10:45

I briefly considered a pair during my repower - was goin to upgrade them to higher hp - bottom line became - sell the lower hp units and buy the 250's rather than begin major parts swaps.

Your milage may vary.

STeveZ · Post by **STeveZ** » Jul 4th, '09, 11:40

Scroll down this thread to see how 6b 210 Cummins perform in my 28 FBC.

http://www.bertram31.com/newbb/viewtopi ... b16674fa0c

In this thread I wondered, and still do, whether I'm better off to run at higher RPMs with more hull out of the water.
Similarly, I wonder about the fuel efficiency of what would seem to be an underpowered B28.

Still, its hard to argue against installing two Cummins engines already in-hand. I wonder if they'd push a Bahia Mar or Moppie any faster?

In Memory Walter K · Post by **In Memory Walter K** » Jul 4th, '09, 11:53

Steve-WOT on the 210's under load is 2650. After re-reading the thread you suggested and looking at your stats I would suggest you might be a bit underpropped. With my heavy hulled, heavy teak decked, big fighting chair, gin pole, radar arch etc., at 2400 rpm (and a clean bottom), I get just about what you do...and I'm a bit underpropped with 20 X 20 mid cupped nibrals. One of us should be doing a little better. Walter

STeveZ · Post by **STeveZ** » Jul 4th, '09, 13:01

WOT is about 2650 for me. For whatever reason it was 2700 on that day, or I misread or misrecorded. I open her up nearly every time I'm out and WOT is 2650. I'll double check this afternoon. (Confirmed)

Here's my prop(s).

If the goal is to hit the target WOT RPM then I think I'm there. If I could swing a bigger or more pitched prop for more speed, what is the down side? One I can think of is that I would idle even faster, right?

In Memory Walter K · Post by **In Memory Walter K** » Jul 4th, '09, 14:24

Yes, that is why I chose to add cup rather than pitch. As I understand it, cupping works on the upper end of the scale and for the kind of fishing I do, the slower I can operate the boat, the better. The guys who have the really bigger hp engines would really need trolling valves for slow operation. On the other end, it is far better in terms of engine life, to be a bit underpropped than overpropped. Less strain on the engine.

scot · Post by **scot** » Jul 4th, '09, 23:12

Major,

The largest OEM installed base of 4BTA 250hp marine engines that I am aware of is in the 28 Carolina Classics. Spend some time on their forum and you will find plenty of guys discussing the 250hp 4B issues and solutions. I recall one of the owners claiming that it was an rpm issue...if he sayed below a certain rpm, the injectors would live. All of them carry spare injectors with them.

http://www.carolinaclassicboatowners.com/forums/

Face · Post by **Face** » Jul 7th, '09, 09:04

I've been restoring my B28 for about 3 years now. I bought the boat with the same Cummins 4BT 150 hp motors. I recently sold my "little" boat and will be getting back to the restoration now that I have the funds. I have ZF 1.5:1 transmissions. I spoke with a gentleman a few years back from a Bertram 28 website with the same setup and he assured my his boat would do 20 knots. He said he had no problem doing Canyon trips with 4-6 guys, gear, ice, etc. I know I'll have a slow boat but it should be excellent on fuel and above all, is paid for. I'll be getting back into the project in the coming weeks...

scooter28 · Post by **scooter28** » Jul 7th, '09, 11:40

face do you still have that lower station that you had talked about selling? also dont forget i think im right across the bridge from you ever need any help or what not im only a stones throw away

Face · Post by **Face** » Jul 7th, '09, 13:39

Hey Scooter, yup I still have the lower station. Send me a pm if you're thinking about rigging it up. I don't want much for it. I think if I ever go back to two stations I'll add a small wheel and controls to the cockpit just for trolling in the Chesapeake. Thanks for the offer for help. I really haven't worked on the boat in a while but I'm getting excited to finish it. Headed to Florida until next week, but when I return I'll get back on it.

Still left, re-install motors and running gear, wire the boat (including new panels), install bow-rail on new pulpit, fill and fair bottom, install hydraulic steering, install controls and new gauge panel.

Luckily I have just about all the necessary parts.

scenarioL113 · Post by **scenarioL113** » Jul 19th, '09, 21:35

I am right smack in the middle of the same conversion. B28 Cummins 4BT3.9m 155HP.

We have spent considerable time fabricating and welding brackets to allow for mounting and have made custom trunnion style hardware to mate up to the mounts.

The original v8 gassers were just lag srewed down into the stringer / beds.

My engine beds are solid and we decided to make c-channel type brackets that lay over the stringer/bed and get bolted through the stringer instead of down into it. They are steel but I will treat them and paint them with good enamel.

I have been trying to do this project with keeping costs down to a minimum. It isnt easy and is VERY time consuming.

I am very satisfied with how the engines are bolted down seems very solid.

I have ZF Hurth 450a2 ratio 1.5:1 and 8 degree down angle transmissions.

I have a set of 18X20 3 blade props and am going to install 1-3/8" shafts.

Unfortunately the hatch covers will need to be raised, I was trying to keep it to a minimum but there are so many things to take into consideration and I can not go any further back because the turbo has about an inch of clearance to the rear.
My trans flange will be more forward than it was with the gassers which means the shaft has to come further into the boat forward, this in turn requires the engine to be higher which in turn causes more hatch clearance issues.

I dont know exactly how much yet but i am guessing it will be about 2 inches maybe 3 at the most, still havent dressed the engines with the coolant reservoir.

With a little luck I may be able to keep the center hatch at stock height (possible but not likely) and then just convert the hatches into a sort od box, not sure yet, I can only process so much at one time in my small mind!

Good Luck!

I will post some pics when I take come.

Any input from others is appreciated as well!

Major · Post by **Major** » Jul 20th, '09, 06:19

What kind performace are you expecting with the cummins 4bt's? I keep hearing that I wont get but maybe 20 mph top speed from them. While atleast the boat would run I was hoping for a little more push. I have already had the decks raised and the shafts changed to 1 3/8" but need two new transmissions. If i can just change out my gearing to match yours ill do that. Otherwise im going to look into a set of twin disc 1.5:1 so my down angle will be 10 instead of 8 degrees.

Im not sure if you have seen one but i have a couple pictures where people have made boxes for the 28. I kind of like them. lll try to get a picture up for you.

scenarioL113 · Post by **scenarioL113** » Jul 20th, '09, 17:36

I am hoping for an economical 21 to 22 knots. If I get that I will be very happy, if its only 19 or 20 that will be ok as well I am no speed monger!

I would really like to see a few pics of any mods to the hatches.

Major · Post by **Major** » Jul 20th, '09, 19:24

Here are some pictures ive picked from boats for sale.

Diesel repower (28 bertram)

Diesel repower (28 bertram)

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