re power 1968 38 Hatteras with 440 HP yanmars

[silverback]

I have the opportunity to repower my 1968 38 ft Hatteras Convertible with 440 HP Yanmars.
Anybody go down this road before?

 

[Freeebird]

 

[Boatsb]

Not personally but they are nice engines. Are they new or did you get some rto's.

My guess is like the 41 and 42 repowers you'll want down angle transmission and may need to increase shaft size. 1.75 may work i c not 2 means new struts.lo

 

[saltshaker]

Not personally but they are nice engines. Are they new or did you get some rto's.

My guess is like the 41 and 42 repowers you'll want down angle transmission and may need to increase shaft size. 1.75 may work i c not 2 means new struts.lo

Aren't those high RPM engines? If so the 1.75" shafts should be fine depending on what gear he uses. Should be an interesting project. Don't see many repowers of the 38C I.

 

[q240z]

Oooo...sounds fun.
The only thing I've heard about Yanmars (aside from that they're great) is that they don't tolerate overloading at all. Make sure they can run all the way up to rated WOT when fully loaded.
And post pix!
Cheers,
Q

 

[REBrueckner]

A possible alternative is high strength Aquamet shafting instead of the standard.

 

[Boatsb]

A possible alternative is high strength Aquamet shafting instead of the standard.

The 38 has 1.5 shafts standard. Converting to 1.75 is possible with thin wall cutlass bearings and machining or changing out the shaft log. I think 1.5 will be far too small for 440 hp.

 

[saltshaker]

A possible alternative is high strength Aquamet shafting instead of the standard.

That's only available for 2 1/2" or larger shafting.

 

[saltshaker]

The 38 has 1.5 shafts standard. Converting to 1.75 is possible with thin wall cutlass bearings and machining or changing out the shaft log. I think 1.5 will be far too small for 440 hp.

I'd think that would be pushing it too far. What RPM does those engines max out at? I remember many of the Yanmars turning in the 3200-3400 range. Might be able to make it work with shallow gears if that's the case. Wouldn't make me too comfortable doing it that way but others have done that with many 36C repowers.

 

[silverback]

Thanks all for the REPLYS, WHAT I FOUND OUT TODAY IS, GEAR NEEDS TO GO FROM 1.4 WHICH IS WHAT THE ZF GEAR IS NOW TO 2.137, WHICH IS WHAT ZF CAN DO WITH SAME GEAR.
Shaft will go to 1.75 assuming struts are thick enough, will find out soon enough. if have to replace struts, project off. have to lift cockpit, pull tanks, not worth it for these engines; they have 3300 hours on them, are in great shape, new heads 500 hours ago, but I just do not fell it is worth that much effort for those engines. Am I wrong?

 

[silverback]

As well, I am hearing from more than a few mechanics that the repair price tag on these guys are enormous. Having tough time deciding. Entry price point excellent, maybe thats why, because after 3300 hours repairs start and it is going to get expensive...ugh. By the way to answer one of the threads, these are 3300 RPM engines.

 

[Fanfare]

I think you can get Aquamet 22 in many sizes. I have 2 inch shafts working well with 550 hp Detroits after 20 years. This was approved by my marine engineer at that time.

 

[saltshaker]

Why do you need to change the gear ratio? The 1.4:1 gears may let you keep your shafts.

 

[saltshaker]

I think you can get Aquamet 22 in many sizes. I have 2 inch shafts working well with 550 hp Detroits after 20 years. This was approved by my marine engineer at that time.

Auquamet22 is available in just about any size. It's the aquamet 22H that is only available in 2 1/2" or larger. The H is a high tensile strength shafting that allows you to use a smaller shaft and still achieve desired safety factors. 550HP and 2" shafts is ok providing the gears are less than 2:1.

 

[Boatsb]

A 38 is considerably heavier than a 36.

Thin wall cutlass bearings will fit the struts and allow a 1.75 shaft.

My 41 has them and they work fine.

 

[jim rosenthal]

3300 hours seems like a lot. Does the price of the engines allow you to have a Yanmar shop go through them while they are out of the boat and freshen them up? Or would that make it too expensive?

 

[Maynard Rupp]

The owners paperwork for our 1986 36 C says that our shafts are 13/4" Aquamet 22.

 

[q240z]

3300 hours seems like a lot. Does the price of the engines allow you to have a Yanmar shop go through them while they are out of the boat and freshen them up? Or would that make it too expensive?

+1
All good questions.
I didn't realize they were high hour engines. Unless they're a scorchin' -- and I mean, like, smokin', lava hot -- deal, I'd be very careful. Yammies can be expensive. I actually looked at a set of 440s for my Roamer, but decided against them in favor of the Cummins Diamonds after looking at parts availability and price, plus general reputation. What you might initially save in re-shafting due to their high speed capability can be easily consumed later (several times over) in major maintenance and rebuilds.

 

[jim rosenthal]

A better way to approach this might be as follows:

You own a Hatteras 38 convertible, which is a fairly rare boat. You want to re-power it. What would be the best diesels to put in there? This is a fairly beamy and heavy boat, appreciably bigger than a 36, if I'm not mistaken. It's also a rather old boat, so unless it's had a lot of updates, you may be confronted with a lot of "while you're in theres" that will need to be done while you are doing the re-power. Assuming you go through with this, I think the best engines would not be Yanmars, but a set of "reman" Cummins C-series at a similar power rating, like 450 hp.

Cummins remans are available at reasonable prices, but they are not going to be as cheap to buy as 440 Yanmars with 3300 hours on them, which are likely to require a rebuild. Mind you, buying a set of Cummins remans is going to be cheaper than buying Yanmars and rebuilding them.

Perhaps the bottom line here is that you are looking at spending a great deal of money to do this correctly, after which you will have a very modern 1968 boat that performs well. If you ever sell it, you are quite likely to take a huge bath on it. Given that older Hatteras yachts that have been re-powered are available so reasonably, you should perhaps look over the market before you start this project. You may be able to find a boat that has already HAD all this work done and you can buy it for far less than you would spend to completely refit your present boat. I'm not scoffing your present Hatteras, far from it, but we all have to deal with these economic realities connected with our love interests.

 

[saltshaker]

I don't think the question here is should be repower and what would be ideal. Sounds like he's getting a good deal on the Yanmars which might make an inexpensive repower viable. I'm not too familiar with those engines but 3300 hours shouldn't be much for quality modern diesels. I would have them thoroughly checked out before getting too deep into it but don't write them off unless 3300 hours truly are high for those engines. Years ago a guy I know picked up a pair of 800HP 3406 Cats cheap. They had nearly 8000 hours on them. He bought them expecting to major them before install. Engines surveyed well and minimal work was done. He ran those for at least another 1000 hours before selling the boat. These engines are far from our old Detroits. If they're decent and priced right, this may be a nice budget minded repower. Not every boat or owner warrant an all or nothing approach.