38 Bertram Repower

Just read this on another thread (one about a 35 Roamer for sale). Seems relevant.

This is NOT a single screw boat. Yes, you can dock it with one engine and a thruster. You can dock it with just one engine. You can run on one engine and compensate with the rudder or a thruster. That's for emergencies only. Doing it on a regular basis is such a bad idea in so many ways.

One of the problems you'll face are that the boat will always want to turn in one direction. You'll have to continually counter that with the rudder and/or thruster. Turning the other way will be restricted. In a heavy beam sea, current or wind you'll have a heck of a time maintaining a straight course. Reversing with only one engine is interesting even with a thruster. The stern will pull to one side. The thruster will bring the bow back in line, but you won't be backing straight in but instead have to calculate where you'll end up as the boat slides to the side. Another is that the engine used will be working very hard to push the weight. Additionally, the prop on the dead side will be freewheeling from the push of the water, but the transmision will not be lubricated and eventually sieze unless the shaft is locked. You'll also find that installing a bow thruster is not a cheap alternative to rebuilding or replacing the motor. Also, if you use the thruster continually for steering it won't last.
Granted for cruising 20 hours a year it hurts to lay in the kind of expense your facing. That's why I suggest going with what's cheapest rather than what may be more right.

find a rebuilt one and stick it in there........you can find them around if you look and it won't set you back anywhere near what you were quoted......or just remove both and stick a single outboard on the transom (after you beef it up) if you want cheap......selling both motors should pay for the outboard......

When I heard 20 hours my mind went to outboards with a laugh. Then I thought about a 70 odd foot FBMY I looked at down in Hollywood only to find it powered by a 115 Merc out back.

If your mechanic is quoting you $60K to replace/rebuild a DD 8-53 he's either stupid or he's looking to screw you. Period.

DD's can be rebuilt for $2K-$3K per cylinder. Not sure how much it would be if the engine has to be pulled, but it sure wouldn't add up to $60K.

What kind of money are you looking to spend?

I assume that the "Harbors newsletter" you refer to is Boats & Harbors (the yellow paper). If not check that. You also might want to check some truck sites. It shouldn't be that rare. I think someone mentioned earlier that you might want to look into a different mechanic or at least get a second opinion. Sounds like he may be trying very hard to get a piece of your pie.

RED:

Keep in mind that the salient feature of your sick motor is that it is a 53-series Detroit a/k/a back then as a GM diesel. That means that there are no small amount of, say, 31 Bertrams (as well as other mfg'ers.) powered by 4-53Ns that likely were re-powered by more modern Volvos, Yanmars, etc., so there may be vintage 53 engines sitting around in boatyards and the like. Ditto for 6V-53s which were OEM in boats built into the '80s. Odds are, the block is fine; might have to straighten a warped head, no big deal, and on such an old engine, you ought to Magniflux (check for cracks) it anway.

Can you bar the engine over? Did it seize to the point that one or more cylinders have the rings stuck to the liners? Pull the heads, drop the pan (roughly a 12-beer job) and see what you've got. These are simple pieces of machinery.

You can remove the turbo's, but you also have to change the fuel injectors for naturally aspirated. There are probably a few other things that need to be changed as well, but most of those parts should be able to be salvaged from your old engines. It should not be a huge deal to make the turbo's into a naturally aspirated engine.

You can also check out http://www.expertdiesel.com

There are 8-53s available on Diesel Engine Trader, Gold Coast Power, Surplus Man, and about a zillion other places, all just a google search away. $60k is a raping price for engines that can be had in good running shape for $3500-5k per, or already reman for less than double that.

$2k per cylinder to rebuild a Detroit? Who would have thought that gold plating would hold up in the liners!

Hi,

Here is another statement that can cause a non mechanical person confusion.

8V 53's are not and will never be Naturally Aspirated they have their charge air pushed into the cylinders by the supercharger.

The supercharger is the thing that sticks up in the middle of the valley where you would see the inlet manifold and carbie on a gas engine.

You should easily be able to re rate those engines back to Non Turbo settings, each injector is it's own HP Fuel Pump so if you remove the turbos and fit the same size injectors as your current engine you will have the same HP as original as long as the timing is the same.

Even if it isn't they were all bolted changes on an 8V 71 so I imagine it would be the same for a 53 Series.

Detroit Diesel calls the entire 2 stroke series without turbo's Naturals, the model designation for his origional engine would be 8v53N and the N stands for natural according to the Detroit Diesel website. So according to the engine manufacturer it is indeed called a Natural.

Hi,

While the model might be described as Naturally Aspirated it is in fact far from that.

I found this description of how it works.

The Supercharger ( Roots blower) mounted to the exterior of the engine provides air at greater than cylinder pressure (positive displacement), and exhausted through two or four exhaust valves per cylinder. The supercharger was used to provide positive displacement, required for a two stroke cycle.

Note the words in bold type, hardly what you would call natural aspiration in real life is it?