Repower questions.....aggghhhh

[richard_kilburn]

Boat - Tayana 42ft (34ft waterline) weight 17000kgs
current engine - Perkins 4.108 49hp.

I'm currently looking at
Yanmar 55hp / 75hp turbo
Nanni 50hp / 60hp turbo / 85hp turbo
volvo 55hp / 75hp turbo

Currently leaning toward yanmar 55
Pro's - Best size and weight
no complex turbo's to worry about
excellent support
good resale value (when I come to sell the boat sometime in the future)
Cons - only 60amp alternator
all access on stbrd side - my access on port side.
need to replace exhaust as well
may be under powered??

I have been reading threads from this and other forums, and I reckon the torque curve on the yanmar 55 and nanni 50 provide almost as much low down grunt as the 75's and 85's. Only difference seems to be when they get over 1800 to 2000 rpm when the turbo's start to increase power and torque

My current Perkins only ever gets to 2100 rpm flat out in forward - which leads me to believe the original prop had way too much pitch for the set up. The Perkins actually rates to 3600 rpm! However, it means I cruise at 5.5 - 6.5 with the engine ticking along at 1600 - 1800 rpm

Therefore I will also look at a new prop - autoprop / maxprop etc - any suggestions / opinions there too would be great.

It's a real pain in the arse and I feel like I'm standing at the bottom of Mt Everest wearing a pair of sneakers and shorts and contemplating the journey ahead! Because of all the work and cost involved with any of the engines above, I want to make sure I make the right choice......

Any help would be greatly appreciated!!!

Richard
S.V Lionheart.

[AnchorageGuy]

we repowered our 14 ton Mariner 40 replacing the old Perkins 4-108 which was way underpowered for the boat with the 56 HP Yanmar. Wow what a difference and the replacement went very easy because of the similarity in footprints, etc.Considered the turbo, but after a few years we are glad we didn't go in that direction. The current engine is fine for the boat and another 25HP would probably be wasted. Not to mention the turbo has a shorter lifespan. BTW, where you guys in the Rio?

[richard_kilburn]

We live on the boat which is currently in Auckland New Zealand. We spent the last season in Fiji.....

[AnchorageGuy]

Must have been another Lionheart. I did think the 42 was a bit heavier than 17,000 lbs.

[never monday]

Originally Posted by Chuck Baier

Must have been another Lionheart. I did think the 42 was a bit heavier than 17,000 lbs.

I think he stated 17,000kg or 37,400lbs

[never monday]

On the T42, I don't see a need for the turbo motors. Like Chuck said it's wasted fuel and energy.
I love the 4JH4E as a replacement for the 4-108. Except in your case. Service side is a big deal when trying to work over the top/side of these engines. I don't remember if the T42 has front access or not, does it? If so, the Yanmar might be the better choice because you'll be able to get to the starter/alternator and raw pump easily with the port access.

[AnchorageGuy]

Thanks for pointing that out Pat, I missed the kg.

[Alan Wheeler]

Hi Richard, and welcome to another Kiwi.
Why do you need to repower? Is the Perkins worn out, or are you not getting the power you want?? Lack of power could be due to the prop being over pitched.

[Just a Tinch]

Personally, if the Perkins 4-108 is doing the job on your particular boat, why not just purchase a "remanufactured" 4-108? It would save you a lot of grief in reconfiguring the motor mounts and all the rest. They are excellent engines, parts are available worldwide, and you already know the engine and its "quirks".

Thats what I would do.

[avazquez]

I have a 4108 that has never let me down. It was totally rebuilt by the previous owner less than 50 hours ago. It works fine but there is always something going on with it. It smokes a lot when initially started, after it warms up it works great, but I have gone through hell and back trying to troubleshoot the thing and stop the smoke and erratic operation when initially started. It is things like these that make me think about removing the damn thing from the boat and just buying a brand spanking new engine. One that starts and runs smooth and that gives you the real horsepower.

[David M]

I agree with not getting a turbo for such a relatively small horsepower diesel. Why increase the complexity unnecessarily?

[Alan Wheeler]

It smokes a lot when initially started, after it warms up it works great,

Without taking this trhead off on a different track, that will be normal operation. As long as you follow the rules of warming up (see the study hall) then the smoke you see if normal. You will never have a clean startign Perkins. Or clean starting anything expcept for the latest generation Volvo's and Yanmars etc. Older engines smoke at start up as a given. It is how well it settles down when warm is your tell tale sign. If it settles down, you have a good engine.
I agree with keeping the perkins however. Great robust reliable engines. But in desperate need of decent gaskets around it.

[richard_kilburn]

Hi Pat

I agree - the access to the oil filter etc is going to be a real pain in the arse. Apparently you can get a remote for the oil filter but again I have heard bad things against that option. Also - we do have access to the front of the engine, and being smaller, the Yanmar should give me more room to play.

[richard_kilburn]

Wheels

Reason for swapping out the 4108 is general age concerns. I spent a lot of time replacing parts / hoses before our trip to Fiji this year, but whilst in Fiji we had several incidents that required new parts and they were all difficult to get (being in remote parts of Fiji). I had to fully service / clean the heat excchanger, repair a couple of hoses, I had the oil pressure alarm sender unit fail and start leaking oil everywhere etc. Since I plan on living on the boat for several years to come, I want to replace with something more reliable / clean (lose the oily bilge). I'm also thinking that when I come to sell the yacht, probably in the US, a 5-10 yr old modern Yanmar will make the boat more saleable (not sailable!) than a 30-35 yr old Perkins.

I don't dissagree that the Perkins is a great motor and will plod along forever, but in our case, I figure the extra cost of putting in the Yanmar is worth it - given the aggrevation of pulling out the perkins to put another in is almost the same apart from the re-working of connections / exhaust etc. In my opinion, the perkins also came with an underrated gearbox, but in our case this hasn't lead to any problems as yet - so after 25 yrs it must be OK. (gearbox is Hurth 100)

[richard_kilburn]

At this moment, my plan is to get the Yanmar 55 non-turbo. I have looked at the torque curve for the 55 against the 75 turbo, and at the lower revs there's very little difference.

For the past 2 yrs, I've lived with a 4108 that won't rev past 2100 rpm in gear. I now realise that this is due to being way over propped. I am planning to install the Yanmar so that max boat speed is reached at full RPM. I am going to look at prop options like Maxprop / autoprop / kiwiprop etc. Has anyone any opinions / experience on these?

Tayana V42's are a heavy boat with a waterline of 34 ft. I often see 8kts under sail but have never managed more than 6kts under power (perfect conditions). I am a sailer more than anything, so the engine really is an auxiliary, however it would be nice to have something that will be able to push into heavy seas and still maintain good forward momentum.