Bertram 25 Repower 470 to 3.0???

[Benjaminlbarker]

Hello,
Long time lurker on many topics. Thanks in advance for all the input from everyone on this forum. I have used it extensively to my advantage not only in my current research but on many boats and engines during the last several years.

I'm the new owner of a Bertram 25 Flybridge. Been eyeballing this boat for quite a while and I believe this is the hull I will die with. (Natural causes I hope. Although redneckism may take its toll) The boat came with Mercruiser 190 s, (470) the engines are not running due to bent push rods caused by stuck valves caused by what is probably manifold problems. Experts can weigh in. The engines have 490 hrs on the Hobbs, 4" exchangers, and alternator conversions. Impossible to get compression numbers on all cylinders but the ones with unstuck valves show 135 to 150psi. Both have clean oil and clean coolant. Been sitting for 14-18 months.

Question: Valve job? Complete rebuild? Swap to 3.0? Or bracket with single outboard?

The power "loss" on a 3.0 swap is not a problem for me.
The current engines are 24" on center, (correct me if I'm wrong) that rules out some options
Any rebuild kit suppliers for the 470 greatly appreciated.

Thanks!

 

[thumpar]

Re: Bertram 25 Repower 470 to 3.0???

The 3.0 would need new drives also to get the ratio down (well number wise up but really down). You are going to have to weight your options.

 

[achris]

Re: Bertram 25 Repower 470 to 3.0???

Pull the 470s, glass up the holes and fit a single big block (8.1 litre) with a Bravo 2 or 3 drive...

I've been lusting over the same boat for many years, and decided if I every got one, that's what I would be doing....

Chris......

 

[nec plus ultra]

Re: Bertram 25 Repower 470 to 3.0???

You won't plane or have fun with a 3.0 (135 hp) in a 25 ft boat. :ballchain:

 

[Scott Danforth]

Re: Bertram 25 Repower 470 to 3.0???

pull the heads, if they are bad, buy a big-block ford head and drill the extra hole.

 

[achris]

Re: Bertram 25 Repower 470 to 3.0???

You won't plane or have fun with a 3.0 (135 hp) in a 25 ft boat. :ballchain:

It has 2 of them, but your statement still holds...

 

[FreeBeeTony]

Re: Bertram 25 Repower 470 to 3.0???

Pull the 470s, glass up the holes and fit a single big block (8.1 litre) with a Bravo 2 or 3 drive...

I've been lusting over the same boat for many years, and decided if I every got one, that's what I would be doing....

Chris......

I like Chris' idea......that would be a great set-up.......

Chris, also wanted to compliment you on your Bahia......that's also a great hull......almost as good as a Grady.........

 

[MarkSee]

Re: Bertram 25 Repower 470 to 3.0???

Not sure where you live but here on the West Coast, we have Skipjacks that are of a similar size and style and many a guy will indeed 'glass in when time to re-power but will then fit with 2 outboards (you listed just one) then use the space in the engine compartment for additional space for placement of coolers/livewell/fuel capacity....of which you now possess a top quality battlewagon for removal of many fish from the ocean.......

Mark

 

[FreeBeeTony]

Re: Bertram 25 Repower 470 to 3.0???

Not sure where you live but here on the West Coast, we have Skipjacks that are of a similar size and style and many a guy will indeed 'glass in when time to re-power but will then fit with 2 outboards (you listed just one)
Mark

Chris is suggesting installing a 8.1L I/O w/ bravo outdrive.......not O/B's.
I have seen similar set-up like you are suggesting with O/B's.......they seem very stern heavy and just don't look right to me....just my $0.02...

 

[Benjaminlbarker]

Re: Bertram 25 Repower 470 to 3.0???

Thanks for all the input. I love the idea of the 8.1 single. I'll have to do some research to see how much modification and cost that would be.

With regards to the 3.0's being underpowered, the boat came from bertram with 120 hp mercruisers and it appears they preformed quite well. The 3.0 mercruisers are 135hp at the prop I believe. Who knows what the 120's made at the prop. Check this table out. Might need to get your glasses.

I am a huge fan of outboards and apparently they do quite well on these boats, despite spoiling the lines.
If I were to go outboard I would put a big single on a bracket. The weight loss in this configuration is staggering and if needed, allows for ballasting to make it trim correctly.

I would love some input or maybe contact info from anyone who has done or knows someone who has done any of these conversions. As always, any opinion or comment is appreciated.

 

[achris]

Re: Bertram 25 Repower 470 to 3.0???

...With regards to the 3.0's being underpowered, the boat came from bertram with 120 hp mercruisers and it appears they preformed quite well. The 3.0 mercruisers are 135hp at the prop I believe. Who knows what the 120's made at the prop. Check this table out. Might need to get your glasses. ....

You are quite right, they did come with a pair of 120s as the standard power (I have an original sales brochure )... Based on that, and some calculation I did a few years ago, a pair of 135s should perform quite well...

I originally had a 165 on my Bahia Mar 20, and it would run at 30 knots flat on a good day. In 1994 I replaced the 165 with a shiny new 4.3LX (180hp at the prop) and it ran to about 38 knots. The calculations (bases on speeds and 180 prop hp) revealed that the 165 was only putting about 117hp down at the back wheel... So, if the new 3.0 engines are putting an honest 135 into the water, they should be better than than with a pair of 165... :noidea:

As for outboard conversions... Never seen one an owner is truly happy with... There are always issues. One of the main ones is that the prop is no longer the same distance behind the transom. That changes the hull characteristics quite dramatically.

I have just been thinking about other options... Maybe diesels? A pair of Yanmar 150s (they come with Bravo 3X drives) or a single Yanmar 260hp (also with a Bravo 3X).... Remember that diesels have a much better torque curve and will seriously outperform petrols of the same hp.... Just a thought... Also remember that with a single engine, that huge engine cover gets to be a lot smaller.

Chris........

 

[MarkSee]

Re: Bertram 25 Repower 470 to 3.0???

Chris is suggesting installing a 8.1L I/O w/ bravo outdrive.......not O/B's.

Not sure why you think I did not understand exactly what Chris was suggesting.
OP mentioned about outboard power in his original post.
I was simply pointing out that here in SoCal guys will keep a Skipjack "forever" and sometimes will re-powered with outboards which to fish safely around the kelp beds here is almost a requirement.

Mark

 

[FreeBeeTony]

Re: Bertram 25 Repower 470 to 3.0???

Never saw these boats w/ less than twin IL6's........
What year is this boat you're looking at?

 

[achris]

Re: Bertram 25 Repower 470 to 3.0???

Plenty still out there with 'double trouble' (twin 470s)...

 

[Benjaminlbarker]

Re: Bertram 25 Repower 470 to 3.0???

Chris, thanks for the input. I would love diesels but they seem to be a bit beyond my price range. Correct me if I'm wrong.

I could rebuild the 470,s and update the drives for around 4 grand. That would leave me with a boat with rebuilt 470's :grumpy:

I could get a gently used outboard, bracket and glasswork for around 10,000.

Option three is the 3.0 swap. These engine packages see to be abundant in the used variety and could be done nearly cheaper than the 470 rebuild. From the merc dealer I was quoted 4000 each or 8000 each with the drives. Anybody had experience with used or older 3.0's? I haven't heard many bad things.

I'm really liking the idea of a big single inboard. How much power does that 8.1 make?

FreeBee Tony, it's a 1968 25 bertram Flybridge. Last repowered in 85, or 86 I'm assuming.

 

[achris]

Re: Bertram 25 Repower 470 to 3.0???

Yeah, diesels are expensive. Couple of years back the wife and I were looking at a 28' Bertram that needed a couple of engines. 2 Yanmar 180s was going to be the best part of 70k... Had the boat been in better condition we would have bought it and done the re-power...

The 8.1 is now an 8.2 and makes 380hp... Check out Merc's website....

 

[FreeBeeTony]

Re: Bertram 25 Repower 470 to 3.0???

The 8.1 is now an 8.2 and makes 380hp... Check out Merc's website....

I'm curious as to what this would cost???
Sounds like the best idea...........
I think a total of 270HP (135 X 2) pushing that Bertram would be underpowered.
I have ~300HP pushing my 24' Grady and it only weighs 4000#........I know that Bertram weighs a lot more than that.
I can cruise at 30MPH @ 3600RPM turning a 17" prop......

 

[achris]

Re: Bertram 25 Repower 470 to 3.0???

I'm curious as to what this would cost???
Sounds like the best idea...........
I think a total of 270HP (135 X 2) pushing that Bertram would be underpowered.
I have ~300HP pushing my 24' Grady and it only weighs 4000#........I know that Bertram weighs a lot more than that.
I can cruise at 30MPH @ 3600RPM turning a 17" prop......

Are they crankshaft horsepower or propshaft? Are you running alpha style drives or bravos or 'other'? As I stated earlier, my old '165' was producing more like 117hp at the prop.... 2 of those would only be making 234hp. 2 new 135hp at the props would be putting 36hp MORE into the water.... I see it as a viable option... (still like one BIG engine though. 380hp into the water would be awesome )

Chris......

 

[FreeBeeTony]

Re: Bertram 25 Repower 470 to 3.0???

I still think 270HP is underpowered............

 

[Bamaman1]

Re: Bertram 25 Repower 470 to 3.0???

Pull the 470s, glass up the holes and fit a single big block (8.1 litre) with a Bravo 2 or 3 drive...

I've been lusting over the same boat for many years, and decided if I every got one, that's what I would be doing....

Chris......

There you go. That's what I'd do. There are online sources of new Mercruiser Inboard/Outboard engines, and they're really good buys for what all you get. And if you can get the job done with a single engine, more power to you. One engine has 1/2 the potential problems of twins, and a new generation engine is even better.

I had a 470 in an open bow runabout, and it ran great. But like so many of them, it blew. It wasn't half the engine the 4.3 engine that replaced it was.