Repowering Bertram 25?

[seo]

Hi, I'm new here, and would appreciate some advice. I have a 1965 Bertram 25' "Bahia Mar" which is powered with a pair of old 165 Mercruisers/chevy 250. They are tired, and I have seen these boats successfully repowered with a single engine. A friend had one with a pair of Volvo 110 hp engines, and repowered with a Mercruiser TRS with a big block Chevy, was pretty happy with it.
My idea is to find a rebuilt or running takeout dual prop outdrive with a big engine. Any advice on the relative merits of Volvo vs Merc for a heavy boat that will be used at 18-24 kt.

This old Bertram was one of first Vee-hull boats ever built, and it 9'11" wide and weighs at least 5,000 Lbs. It's a 22? Vee all the way to the stern, and is not an easily driven boat. I don't know if a 350 GM engine is enough to drive it, or if I need a big-block, which I think would weigh about the same as the pair of 250 Chevy sixes.

I have no interest in going super fast. The boat is used to get across the bay to an island in Penobscot Bay, Maine, which I do in all seasons, usually hauling the boat out January-March. I used to sail as engineer on tugboats, and am a pretty good mechanic, so the 250 Chevy engines were okay except that they're salt water cooled, the outdrives were wearing out, and they burn a lot of fuel. My hope is that a fuel-injected engine with a duo-prop drive would be more efficient. As built the old outdrives are quite close together, with props turning the same way. The boat will barely twist at all with the engines, and I essentially handle it as if it were a single-engine boat.

The installation work and glassing up the old transom cut-outs is no big deal around here.

Any advise, opinions, comments, or leads on good deals on appropriate engines would be much appreciated.

SEO

 

[Don S]

Re: Repowering Bertram 25?

Having run both the Bravo3 drives and the Volvo drives, the Volvo drives are WAY better in effeciency in getting on plane and economy. The Bravo is better in top speeds. Mostly because of the prop designs. The Volvos have 2 completely different props tuned to work together. Bravo has 2 identical props except one is LH one is RH. Same diameter and same pitch.

Might want to play with the engine configurator in the link below.
http://www.volvo.com/volvopenta/glo...s/engine_configurator/engine_configurator.htm
If you are looking for a Volvo big block, stay away from the 740 series, you don't even want to deal with the manifold and cooling system problems involved with that engine.

 

[Bondo]

Re: Repowering Bertram 25?

Ayuh,.... Welcome Aboard Seo,...

The Cheapest way to go is to find a boat with the driveline you Want,+ Junk it out....
Otherwise,...
You're looking at spending a Major chunk of Ca$h for your repower....

That said,...
The Merc. Bravo III, or the Volvo duo-prop will work just Fine...
The Biggest difference is which 1 you can easily get Parts for...
Which of course depends on the local Dealerships in your area....

Ideally,... A Diesel Volvo D-P would be a Great choice for a Great Classic hull like your Bert....

 

[Don S]

Re: Repowering Bertram 25?

Ideally,... A Diesel Volvo D-P would be a Great choice for a Great Classic hull like your Bert....

I agree 1000%.
When you go to the engine confiurator link look at what a the Volvo D4-260 with DP-H drive will give you.
I know it was enough to push a 28' Bayliner to 38MPH at WOT using only 9 gallons per hour. You can expect a big block to be about double.

 

[seo]

Re: Repowering Bertram 25?

There are advantages to diesel, but it's not like the good old days of my childhood when diesel cost .09, and gasoline was .28 or so. In today's world you're pretty much buying fuel by the Btu. I have a couple of trucks with 454 GM engines in them, and my experience has been that if you run them at about 70% power setting, between 2800-3400 rpms they're not too terrible on fuel. But when you are running full power they really slug down the gas.
I'll be very interested to try the Volvo software test. My guess is that it would take a D6 to give good performance without running at ridiculous boost pressures.
I used to own a boat, 63' displacement hull with a pair of Volvo TAMD 70E engines. I'd go about 9 Kt at 1800 rpm, 6 Lbs. boost, burning around 7gph for both engines together. To get 11.5 kt I'd have to turn 2400, 26 Lbs boost, burning maybe 30 gph.
My father used to point at the boost guage on machines he owned, and tell me that it was the "Hours between overhaul" gauge, in reverse.

Given the expense of Volvo stuff, I'd almost be tempted to try to match a Cummins B model to a Volvo DP outdrive. Between the pickups and the lobsterboats, they're everywhere up here.

SEO

 

[TilliamWe]

Re: Repowering Bertram 25?

... Bravo has 2 identical props except one is LH one is RH. Same diameter and same pitch.

While everything you said above is accurate, this statement is not Don. Sorry. The rear prop on a Bravo 3 does have the same pitch, but it is indeed 1" smaller in diameter. If you go to prop pages to buy a set, you'll see the diameters listed. Also, the diameters get small as you go up in pitch. Kinda like all Bravo 3 props start with the exact same amount of steel and by twisting the blades more to get more pitch, it decreases the diameter.

But I do believe you that the VP DP is more efficient. VP had to have a reason to make the rear prop so much different than the forward prop. And they've been doing it longer too.

 

[Don S]

Re: Repowering Bertram 25?

While everything you said above is accurate, this statement is not Don. Sorry.

Ahhhh, maybe Merc finally figured out they need to be different because of the different flows. They used to be the same, except for direction (and prop shaft size).
No need to apologize, I am wrong at times.

 

[abj87]

Re: Repowering Bertram 25?

the new yanmar sterndrive looks pretty interesting.
http://poweryacht.blogspot.com/2009/01/propulsion-yanmar-sterndrive-zt350.html

 

[seo]

Re: Repowering Bertram 25?

the new yanmar sterndrive looks pretty interesting.
http://poweryacht.blogspot.com/2009/01/propulsion-yanmar-sterndrive-zt350.html

When they first came out, the Yamaha outdrive looked good too. And then it disappeared from the market. I wonder if their customers were able to get parts...
I know that Yanmar isn't Yamaha, but the situations are similar. And their is the similarity of their names, with all those Y's and A's. Hmmm...

 

[Don S]

Re: Repowering Bertram 25?

After dealing with prices of parts for Yanmar diesel engine and their warranty and customer service a couple of times, I wouldn't even consider the engine, which was used with the Bravo drives for years, let alone the drives.
The prices for things like oil and fuel filters made the Volvo prices look like they came out of Wal Mart or cheaper.

 

[abj87]

Re: Repowering Bertram 25?

I don't know much about the drives, but there diesels are pretty decent. They also sell diesels mated to bravo drives too. You got a lot of options here do your research!

on an off note which island in Penobscot bay? i have done some sailing in that area.

 

[HT32BSX115]

Re: Repowering Bertram 25?

Howdy,

A much as I like dual prop drives, Those 6cyl GM engines are probably some of the best engines ever made for boats. They're reliable and quite fuel efficient.

You might take a pretty hard look at just rebuilding them and putting new SE drives on it.

Dual engine redundancy might be a plus here.



Regards,


Rick
(yes, the prop on the right is about 1" smaller dia than the left!)

 

[seo]

Re: Repowering Bertram 25?

I do wonder about repowering with 165 Mercs, and keep my eye out for a pair of them. The engines in the boat now are salt water cooled, and I think they've had it. I have one freshwater block that's rebuildable, and would have to find another, and outdrives as well. It would keep the boat "original," which might enhance its value to a collector, but I'm not sure it's a collector's item. The old Merc outdrives, with they're dog-clutch shifting, ignition interrupters, and foolish little "shift shafts" seem like really bad design. In contrast, the Volvo monoshift is a really clever, simple, design, and seems to have worked out well, at least in the lower horsepower models.

The thing people keep telling me is that if you want low resistance and high speed, get a Merc, if you want durability, get a Volvo. If you want trouble, get an OMC King Cobra.

Is it true that after a certain date the King Cobras were actually designed and built by Volvo?

Does anybody remember the OMC outdrives with the electric shift? Are any of them still running?

I don't see any advantage in twin engines. If I was worried about the main engine breaking down, I'd probably get an outboard kicker, and from what I've seen a 15 hp will move the hull at about 5, which is about what one of the 165's by itself will do.

Volvo makes good engines, and I actually used to be a Volvo dealer, and have owned and run them. But the parts are expensive, and they've almost disappeared out of commercial boats up here, being replaced by the B model Cummins on the small end, and by the new generation of Cats on the higher horsepower end.

Steyrs are really interesting engines. As least some of them use a one-piece casting for block and head, which allows better cooling, no head gasket failure, etc. It also means that if you have one burned valve the whole engine is coming out, and you have to pull pistons to get at the valves. I'm willing to believe that's a logical trade-off for the reduced weight and improved efficiency, but right now the source of parts is very expensive. Supposedly Steyr has some shared ownership with BMW, and the new generation of Steyr diesels are used in Europe in some BMW cars. The BMW labeled marine engines from back in the '80's were actually Steyrs for the bigger engines. The little sailboat engines were made by Hatz.

Right now, today, the B model Cummins is the most widely used diesel in Maine, between the Dodge pick-ups and all the lobsterboats that use them. I think they're also used in some Case/IHC tractors, but could be wrong about that. Usually that translates into wide availability of parts, lots of mechanics who understand them, and relatively good prices.

One engine that I wish they'd do a marine conversion on is the four-cylinder Mitsubishi that they use in all those little Mitsubishi Fuso trucks. Mechanics speak very well of them, and they are supposed to be quite economical and rugged, with a good horsepower to weight ratio. I have been told that the current crop of small Caterpillar crawlers are in fact Mitsubishis with Cat stickers on them, but don't know if they use the Fuso truck engine.

 

[chiefalen]

Re: Repowering Bertram 25?

No disrespect, to the original poster and all the people who replied, but did you do a compression check on these motors ?

The reason i asked this refit your talking about on a 1965 boat is going to cost big, big money.

This is a wood boat?

You are willing and able to spend this kinda money on this boat?

The motors in the boat now where installed when ?

My very best friend in this world has a house up in Maine right down the road from the water sprout. His mother used to work at the Samoset.

I'm just interested in what the compression is on both motors.

 

[Don S]

Re: Repowering Bertram 25?

Is it true that after a certain date the King Cobras were actually designed and built by Volvo?

Yes and No.
OMC and Volvo went into a joint venture in 94. The drives still looked like a Cobra, but the insides were completely different. The SX drive looked like a Cobra externally, but all Volvo cone clutch inside.
Then in 98 Volvo bought out OMC completely, and the sterndrive section of OMC ceased to exist.

 

[chiefalen]

Re: Repowering Bertram 25?

Yes omc electric shift drives are still being used today. And i hate them, the very design offends me. I had 2 apart on my bench with the manual opened and i can say with certainty it's not a drive you wish to tangle with.

I have the the last of the stringer series omc drive on my boat, that one i can live with.

 

[FreeBeeTony]

Re: Repowering Bertram 25?

I would vote to rebuild the IL6's and replace the drives w/ SEI's as previously suggested. The IL6's are simple to work on and parts are available.........you can even find remanufactured ones online.

 

[HT32BSX115]

Re: Repowering Bertram 25?

Volvo makes good engines

If you're talking about engines, they're both (Merc/Volvo) good engines built by GM Powertrain.

If you're going to be doing your own work and you're going to maintain them, you'll have an easier time finding Merc parts. At any given time you'll find about 3 times more new and used Mercruiser , engines, drives, props, gimbles, trim pumps, cyls, etc on ebay than for Volvo.
(just now, a search for "Mercruiser" in EBAY's "Boat Parts ACC & Gear" produced 2461 Mercruiser hits", and a search there for "Volvo" produced 758.

If you're talking about who designed what, The first commercial Volvo sterndrive was "invented" by a Kiekhaefer Mercury engineer.

It doesn't really mean anything. today, Volvo produces probably one of the best stern drives on the market.

I HAD one of those wunderful OMC (460) King Cobras hanging off the back of my 21ft boat. If I had found a Volvo Penta BBC/DPS first, that's what would be there now!

I just found (locally) the Merc first. (actually I found several......I never did find any complete Volvo engine/drive combinations)

I also priced it buying new. Both 496 /8.1L engine/drive combos from Volvo and Merc were similarly priced at the dealers in Portland, OR I spoke to.....

If you're going to replace the long blocks, you could also add closed cooling to them These people (among others) have them for the 165,
they're San Juan Engr kits.


If I was going to operate in the ocean in all weather I would think twins might be better....( I have a hard time believing that a 15hp "kicker" pushes that boat as well as a good running single 165)


Good luck!



Rick

 

[chiefalen]

Re: Repowering Bertram 25?

HT i ignored the 15 hp pushing the boat the same as a 165, cause i didn't want him thinking i was attacking him.

15 hp will barely give him headway if that, and a good wind or waves forgetaboutit that 15 and that boat ain't going nowhere.

Still waiting for the compression test. Maybe there ain't nothing wrong with them motors, and it's a desire for more power.

2 motors, are the safest way to go on the water, one motor goes down the other will get you home.

I myself now have a kicker motor strapped down in my cuddy, and i hope i never have use for it.

 

[Fishermark]

Re: Repowering Bertram 25?

Does anybody remember the OMC outdrives with the electric shift? Are any of them still running?

I have one sitting out by my shop - you can come and get it for free!! Even has an old boat attached to it that I will throw in with the deal!