Repowering A 58TC

[Sparky1]

First, I realize I've been crying wolf on this rebuild deal for quite some time now, but I simply have to do something with my 58. I still don't know exactly what it's going to take to rebuild the starboard that has a burned piston, but given today's climate, I'm thinking of other options including a repower with smaller engines. Truth is, I really love this boat, and I'm not going to just give it away.

Hull speed for my boat is approximately 10 knots, and now that it's destined to become a river cruiser, that's really all the speed that's practical not to mention economical. Having run this thing over 1,000 miles on one engine has let me realize that making 10 knots is not that bad. I'm also considering the possibility of putting the boat into a river charter as a bed and breakfast type operation as it's located in a prime area for such a thing.

I'll try not to ramble too much on this one, but I'm looking for ideas as to how 671N's, for example, may work on this boat. I realize there are more efficient engines to be had other than the 671's, but I doubt the difference in cost would justify them. No doubt there would be a huge weight savings which would further enhance fuel economy. I'm assuming I could sell my 12V71N's for enough (or close to it) to come up with a pair that have been rebuilt. The port engine runs like a top and has less than 1,000 hours on it.

My questions are as follows:

Will 671N's be sufficient to provide hull speed without overworking them?

Can I change gear ratios in the transmissions to allow using my current props and shafts or am I looking at replacing those as well?

Last but not least, has anybody heard of anyone doing such a swap in this model?

 

[Boatsb]

Thats less than 3oo HP for the 671N. I bet you can get hull speed. Probably easily. I also know of a member with TI's looking to sell them and they are running. If they were put in the boat as they are now ( I think 475HP ) you may still be able to plane.

 

[garyd]

Great idea to repower and reduce weight.

I suggest you remove both engines and add two paddleboat saddles in their place. Of course you would have to add a mount for the front of the shaft with a bearing and a 90 degree gear but all eaisily done.

Now with the bed and breakfast add that you have an exercise room and the first excersize is 10 reps of 5 minutes on the stationary bike.

The guests will be peddling away while you navigate and captain the ship from port to port. No fuel costs happy healthy guests everybody wins. I'm sure Pascal will be your first paying customer. LOL

Run silent run true

garyd

 

[ThirdHatt]

Okay, I'll respond in all seriousness in hopes it will do some good.

Randy, I think any repower whatsoever even with 6-71's will cost you more than just repairing the damaged engine. I will probably catch hell for this suggestion, but boating on a budget means cutting a few corners sometimes. Nobody said you have to do a full rebuild on that engine! If you have a burned piston, just replace the one cylinder kit and put the engine back together. That will be your very least expensive option and you're back in business. Done.

6-71's work great in powering the heavy 58LRC's at hull speed and some 58LRC's even get by with 4-71's so you would certainly be able to make that work in your boat. You would want naturals, not the high HP turbocharged 6-71's that have a short lifespan since you're converting to a trawler. I am not sure if one good used 12v71N and one that needs rebuild would sell for similar money as a pair of rebuilt 6-71's but who knows. Even though 12's are twice the motor, they are not worth twice as much because they cost twice as much to rebuild.

Assuming you could find the right deal and not have too much out of pocket there you still have to get the old motors out of the boat, re-engineer the engine beds for the 6-71's (or whatever you end up finding the right deal on) and get the new motors installed. Even doing alot yourself and with lots of help from friends, I think you will still be spending well into 5 figures. I really think that in the long run no matter how many ways you look at it the least expensive way to fix your problem is simply to fix the damaged engine. You won't lose any of the boat's value or desirability that way either because it will still be as Hatteras intended it to be.

 

[SeaEric]

Randy, I think any repower whatsoever even with 6-71's will cost you more than just repairing the damaged engine. I will probably catch hell for this suggestion, but boating on a budget means cutting a few corners sometimes. Nobody said you have to do a full rebuild on that engine! If you have a burned piston, just replace the one cylinder kit and put the engine back together. That will be your very least expensive option and you're back in business. Done.

Well said. I agree. If she were my boat, this is what I would do. Barring other unknown damage or the famous "while you're in there's", just fix what's broken.

 

[Capt K]

All seriousness aside, maybe you could bring it to Ct and we could figger out what to do next. If, after a couple months of brain storming (with lubrication, of course), maybe we could start a poll for further ideas.

I'm sure I could arrange a slip for you somewhere near me or Nick.

K

 

[MikeP]

Concur w Eric/Third - don't reinvent the thing. Just do the necessary repairs. These engines were designed with that in mind - you can easily repair one cylinder/associated parts.

 

[captddis]

I fourth it! It will cost more to repower than to fix or replace the 12.

 

[Genesis]

I'd fix the busted hole.

Ns? Likely the rest of the motor is ok. Fix the one.

 

[Sparky1]

Thanks for the input guys (except Gary of course ) as I do appreciate it. No doubt the first priority is to get into that engine and find out exactly what it's going to take to get it up and running again.

Given the way the engine still ran when it was together, I really don't think the bottom end is going to be hurt. If it is, then the repower scenario may not be a bad way to go. Dave's friend Roger who serviced my port engine before the big trip gave me a worst case scenario of $30K if we went the new Reliabuilt long block route. I've gotten quotes all over the place for a rebuild, so who the hell knows what the bottom line will be assuming the crank is good?

There's a very good chance this 58 may be my last boat, so I'm looking at the big picture here. I would think I could almost double my MPG with the 6's vs the 12's. As for positioning the 6's in place of the 12's, I'm no expert, but it seems to me that would be no big deal just to move the rear of the engine to the same position on the stringers as the 12 was. Will the transmissions (Allisons) not be the same on the 6's?

 

[Boatsb]

Most 671's have smaller transmissions and of course the mounts will need to be re done. The cost of all that work will not be cheap unless you hire illegals.

I would guess ( I have done repowers before but not 12v71's ) it will cost every bit of 12K just to get the old ones out and the new ones in. Not including cranes, Glass work and such. $3-5K or more

Say the 2 671's cost $10K each. Now the $12K to do the swap. That's more than a rebuild and you no longer have the ability to plane. Even if you get 10 for the RTO engine I don't see the benefit.

 

[ThirdHatt]

Scott is right Randy, forget about the repower and just fix what is broken. Using different Detroits is exactly the same as using any different engine, everything will be different and the engine beds, hoses, cables, wiring, etc. will need to be set up for the changes ($$$). We can guess all day what a repower might cost but even the best guesses are way more than just to fix what is broken with your engine. Those $20-30k estimates are for FULL rebuilds, whether on yours or swapping for another like engine.

You said the engine ran so the bottom is likely just fine. Find a REAL Detroit mechanic and simply have him swap out just the ONE cylinder kit that is burned and button the darn thing back up. Yes, it really could be as simple (and affordable) as that. It starts to get very expensive when you over-thiink this and that is what may have been (and still?) holding you up.

Using the widely accepted $3k per hole cost estimate for a rebuild, you could easily be done for as little as $5k (allowing for other minor expendatures), as opposed to 4 to 6 times that! Now THAT is an affordable answer to your problem. Heck, you wear that on your wrist! LOL

SO, anybody know a good Detroit mechanic in Tennessee?

 

[Genesis]

These are naturals guys.

They're not highly-stressed turbo motors.

Pull the head, drop the pan, pull the one cylinder kit, replace it.

Put it back together.

Couple of day's worth of work, done careful and right, maybe three (you gotta re-tune it when you're done.)

You're talking three, four, five times as much money to pull and replace with 6s, assuming you get the 671s for FREE, which you won't. The mounts have to be redone, the wiring is different, and you have to crane and jack all the stuff around. That's going to be a major pain in the ass; I wouldn't even consider it.

You can buy a LOT of fuel for the difference in cost.

Just fix the busted parts and be done with it.

 

[spartonboat1]

Concur w Eric/Third - don't reinvent the thing. Just do the necessary repairs. These engines were designed with that in mind - you can easily repair one cylinder/associated parts.

Supposedly in WWII there were many cases of DD's (GM Diesel then) running around with missing pistons. I am not by any means suggesting that. But I agree with do the one kit, unless the others have cracked rings or serious compression issues. That is, if you are willing to do it on the cheap.

 

[SKYCHENEY]

Forget the engines. Its just a riverboat. Mount a couple of outboards to the swim platform and call it good.


But seriously. I agree with the fix what you have principle. That has been what most have stated here ever since you had the problem back in Florida.

 

[ThirdHatt]

Are the heads still on the engine? I seem to recall something like they were pulled off down in FL and went to a shop and that is when the work stopped due to huge cost estimates for a rebuild.

Did that guy ever bring your heads back to the boat after you declined the full rebuild? Have they been taken care of so that they didn't corrode up on you in the mean time? These things could certainly add to your costs.

 

[Brian Degulis]

You know what I'd repower it. Sure you could fix one hole probably last forever at hull speed. But with fuel being what it is I think re powering the right way is your best bet even for re sale. But forget the 671s that would be insane. A pair of completly rebuilt 671s will cost the same as a new modern engine so don't invest in the past. If it was my boat I'd put in a pair of cummins QSB 230s size them up with deep enough reductions to turn the props you have on there now. I'd also put them in on floating mounts with Aqua drives smooth and quiet like you can't believe. I'd consider cutting a section out of the hull side below the vent in order to get the stripped down 12 out and the new in. Yup I'd make a modern fuel eficient hull speed boat out of it.

Your first thought was right there you freekin trouble maker stick with it!!!

Brian

 

[Walter P]

Hey Randy,

You could fabricate some sort of "sea drive" brackets on the stern and run a couple of 4 stroke outboards on it you know. The advantages would be many...such as no more through hulls for raw water intake, no exhaust system to take all that space under the dressers in the staterooms, no more engine alignment issues or leaking stuffing boxes and the list goes on. PLUS you end up with a very large space formally used to house all that iron to do with as you please.

Hummmm, this post started as a joke, but maybe......

Walt

 

[holtcl]

Randy-

Get in touch with Diesel Don- he can help you 256-259-7728. Highly recommend talking with him before you make any decisions on this. He does the majority of the diesel work in your area. Good luck!

 

[bobk]

Randy, I'd second Diesel Don, but seems to me you already have talked to him. He aint cheap though, but he does know Detroits.

Bob