Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 15-11-2007, 13:48   #16
Registered User

Join Date: Oct 2007
Location: Southern California
Boat: Was - Passport 45 Ketch
Posts: 837
Quote:
Originally Posted by richard_kilburn View Post
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.
These are contrary statements.

If you have heavy seas, why would you want to motor into them?? Just curious. Sorta sounds like you want a motor-sailor.

I'm not sure why you think motoring a sailboat at 6kts (144 miles per day) is not a good thing. That's sorta normal for that size vessel. Any more than that and you are just pushing fuel and $ out the exhaust pipe.

You may be wise to stay away from turbos. Just something elso to go wrong IMO. 55HP is huge for that boat. You'll brobably be able to push her at 7.5kts (180 miles per day)......but you've gotta ask yourself....why?? . Is 36 miles per day worth that much $ to you?? So, you get to port 1/2 day faster (if you are becalmed somewhere). What will you do with all that extra time??

It's your $ and maybe you have plenty of it. If you do, the Yanmar 55 is a great engine. Myself......I'd keep that 4108. They last forever but they are noisier. If it is having a problem (doesn't sound like it is) get it fixed. Sounds to me like you may do well pulling the injectors out and getting them serviced and have the prop re-pitched so that you can use the HP that the engine has. JMO.

If you are only getting 2100RPM out of that engine (with a clean boat bottom), you are working at about 60% efficiency. No wonder you are frustrated. However, a new engine may not be the best or most efficient solution.
__________________

__________________
Kanani is offline   Reply With Quote
Old 15-11-2007, 13:56   #17
Registered User

Join Date: Nov 2005
Location: Ohio
Posts: 2,313
You might also consider a Westerbeke. We have the 108C6 and have been happy with it. We yanked the old one with 6,000 hours and installed the new 108, mated to a Velvet Drive, and turning a Max Prop. Very happy with the setup. No turbo.

Oh, and you can get any alternator you want.

Westerbeke Corporation: Deisel Engines
__________________

__________________
Joli is offline   Reply With Quote
Old 15-11-2007, 14:10   #18
Registered User

Join Date: Nov 2007
Location: SE Asia
Boat: Belize 43
Posts: 15
Quote:
Originally Posted by Kanani View Post
These are contrary statements.

If you have heavy seas, why would you want to motor into them?? Just curious. Sorta sounds like you want a motor-sailor.
Let me clarify, there are certain circumstances where you simply have to motor into heavy seas for a short period of time - we had a couple this year in Fiji getting through reef passes where you have little room for maneuvre. In one particular case we were trying to round a reefed headland and the 4108 struggled. Having sails up would have been pointless given we were heading directly into wind. It is extremely rare, but it's nice to know you have a bit up yer sleeve for situations that call for it.

My passage from Fiji to NZ this year saw the 4108 break down due to air in the high pressure pump to injector line due to a crack. This meant 4 days of beating to windward and then sailing to Q-dock in Opua. Another reason the 4108 got the thumbs down. Again, nothing wrong with the core engine, far from it, but the age of the peripherals letting us down at a very bad time. We were lucky in that we had a BFH (1030) to get us to NZ, but in other weather patterns we could have been hammered.

Quote:
Originally Posted by Kanani View Post
I'm not sure why you think motoring a sailboat at 6kts is not a good thing. That's sorta normal for that size vessel. Any more than that and you are just pushing fuel and $ out the exhaust pipe..
Totally agree - I motor at 5.5kts normally. However sometimes you find yourself in situations when you simply can't maintain 5.5kts as above. They are rare, but do happen occasionally.

Quote:
Originally Posted by Kanani View Post
You may be wise to stay away from turbos. Just something elso to go wrong IMO. 55HP is huge for that boat. You'll bropably be able to push her at 7.5kts......but you've gotta ask yourself....why?? ..
When installing marine engines, the industry std is to install an engine capable of getting the boat up to hull speed (heavy displacement yachts) at full revs. According to Tayana - that means something from 50-80hp for the Tayana 42. Most people have commented that a Yanmar 55 is on the small side for the yacht! Terminal hull speed is just under 8kts.

Quote:
Originally Posted by Kanani View Post
It's your $ and maybe you have plenty of it. If you do, the Yanmar 55 is a great engine. Myself......I'd keep that 4108. They last forever. If it is having a problem (doesn't sound like it is) get it fixed. Sounds to me like you may do well pulling the injectors out and getting them serviced and have the prop re-pitched so that you can use the HP that the engine has. JMO.
If I was not planning to live aboard for the next 10 years and cruise remote parts of the planet - I would totally agree. And unfortunately I don't have lots of $$$'s hence why I'm doing the install myself. That way I can learn about the boat, do some re-wiring and re-plumbing while the engine is out, and clean up my oily bilge!
__________________
richard_kilburn is offline   Reply With Quote
Old 15-11-2007, 14:29   #19
Senior Cruiser
 
DeepFrz's Avatar

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Winnipeg
Boat: None at this time
Posts: 7,930
Don't size your prop to small. You want to leave 3 to 5 hundred rpm. less than max. at the top. Check out the online prop. calculator and you may find that the prop. you have will do very well with one of the available transmission ratios.
__________________
The Blue Dot Campaign. This Changes Everything.
DeepFrz is offline   Reply With Quote
Old 15-11-2007, 15:22   #20
Registered User

Join Date: Jun 2005
Posts: 1,901
Quote:
Originally Posted by DeepFrz View Post
Don't size your prop to small. You want to leave 3 to 5 hundred rpm. less than max. at the top. Check out the online prop. calculator and you may find that the prop. you have will do very well with one of the available transmission ratios.
Gotta disagree

Prop the boat so it will achieve the highest SOG for the maximum RPM of 3000 on the 4JH4E.

The 3000 number is a MAX rating and should not be run at that speed for more than 60 min. Maximum continuous rating is 50hp@2907 RPM, this can be run all day long until the cows come home.
THis leaves you with a one hour reserve built in.
__________________
never monday is offline   Reply With Quote
Old 15-11-2007, 15:41   #21
Registered User

Join Date: Mar 2007
Location: Kapiti Coast, Wellington
Boat: Farr 46 Centre Cockpit Fractional Sloop
Posts: 66
Hi Richard

I had exactly the same problems with my Perkins 4-108 - max revs 2100. My problem was a bit more complicated (see my Rusty Valve Thread) but the main problem was over-propping. The 4-108 is nowhere near its ideal rev range at 2100rpm. I believe your 4-108 is the "New" model like mine. These are rated at 51 Hp at 4,000 rpm. If you examine the HP curve you will see that at 2100rpm you are closer to 40Hp. When you take off the HP absorbed by the alternators, gearbox, shaft bearings, etc you begin to see the problem. In my case I am keeping and rebuilding my 4-108 and re-propping to run between 2400 and 3000 rpm where it will be in a much more efficient portion of the power and torque curves.

I, too, loooked at the Yanmar 55HP option vrey closely. I had the same issues with my boat being set up with best access to the left side of the engine, but most compelling was the total cost of the change - when I added up everything. My total for changing to the Yanmar was very close to $30,000 as opposed to around $10,000 for the rebuild option.

If money was no barrier I would have gone the Yanmar way and lived with less than ideal access, but I have more pressing things to spend the $20,000 on.

BTW is that your 4-108 for sale on TradeMe?

Cheers

Mike
__________________
Mike from NZ
Farr 46 Cruising Sloop
Mana, Wellington



MikeNZ is offline   Reply With Quote
Old 15-11-2007, 16:00   #22
Registered User

Join Date: Nov 2007
Location: SE Asia
Boat: Belize 43
Posts: 15
Hi Deepfrz!

Can you point me in the direction of the online prop calculator? I reckon you're right, but the one I've got at the mo is far too over pitched - given I can't get the engine past 2100 and it should go to 3600......could also be something wrong with the engine, but it seems to run fine.
__________________
richard_kilburn is offline   Reply With Quote
Old 15-11-2007, 17:30   #23
Registered User

Join Date: Nov 2007
Location: SE Asia
Boat: Belize 43
Posts: 15
Quote:
Originally Posted by MikeNZ View Post
If money was no barrier I would have gone the Yanmar way and lived with less than ideal access, but I have more pressing things to spend the $20,000 on.

BTW is that your 4-108 for sale on TradeMe?

Cheers

Mike
Yep - it's the one on trade-me that sells on Monday. Had a couple of guys look at it already - it's a great motor cos of the rebuild in 04.

I don't have heaps of cash - but I worked out that the cost difference was closer if you include your time and then the additional stuff I want to do to the boat while the engine is out. Plus at the end of the day, the boat is more saleable with a far newer yanmar than an ancient perkins.
Also - the wife is working at the moment and she's really keen on the engine so who am I to argue! She'll probably end up paying for most of it - I just have to fit the bloody thing!

Big thanks for the calculator offer!

Richard
__________________
richard_kilburn is offline   Reply With Quote
Old 15-11-2007, 17:33   #24
Moderator
 
Boracay's Avatar

Cruisers Forum Supporter

Join Date: Feb 2004
Location: Pelican Bay, Great Sandy National Park
Boat: Steel Roberts Offshore 44
Posts: 5,175
Images: 18
And now for something completely different...

In a similar situation to you (though my engine was far worse) I elected to go with a John Deere 4045 mated to a ZF 63 box. 75 genuine clydesdales from 4.5(yes that's 4.5, not 2.2) litres.

Price was $20k as opposed to $16k for the 55 hp Yanmar.

I could not find a mechanic to install the engine but the John Deere rep. (Thanks to Paul Gwyne) worked with me and I did it myself. Took three months.

Installation costs came to around $4k. (Custom welding, engine mounts, hoses etc.)

I am going to get the prop repitched next time I haul.

I have used the following sites to calculate my prop specs. The seem to have some connection to the real world.

I used 46% slip as suggested by Gerr.

Prop diameter calculator. Scroll down to Exalto Holland's nomogram

RBBI Prop Calculator.

BoatRamp.com prop calculator.

ContinuousWave prop calculator.
__________________
Rust never sleeps
Boracay Blog.
Boracay is offline   Reply With Quote
Old 15-11-2007, 18:07   #25
Registered User

Join Date: Mar 2005
Location: FL
Boat: Far East Mariner 40
Posts: 652
I have a Mariner 40, around 27000 lbs, I repowered with a Westerbeke 64. I turn an 18x15 prop and run it around 2000 to reach hull speed. Max RPM for this engine is 2800. Fuel usage is good, it is quiet and seems to run very well. I only have 60 hrs, so almost too new to assess. But at this point I really like it.
__________________
Islandmike is offline   Reply With Quote
Old 15-11-2007, 21:56   #26
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
Quote:
Let me clarify, there are certain circumstances where you simply have to motor into heavy seas for a short period of time -
Yeah, it's called sailing in NZ. :-)

Quote:
Don't size your prop to small. You want to leave 3 to 5 hundred rpm.
Absolutley wrong. You need to be close to full RPM. A max of 10% less is OK. No further.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 18-11-2007, 12:50   #27
Registered User

Join Date: Nov 2007
Location: SE Asia
Boat: Belize 43
Posts: 15
Quote:
Originally Posted by Alan Wheeler View Post
Yeah, it's called sailing in NZ. :-)


Absolutley wrong. You need to be close to full RPM. A max of 10% less is OK. No further.
Hi Alan

I have now spoken to about 5 prop / engine specialists and they all agree that max boat speed should come at max engine revs (for the given engine). I now know that my existing prop is over pitched and that the new one will be designed to hit max speed at max engine revs. I'm guessing one of the previous owners thought it was a good idea to over prop for some reason. The perkins I have has never burnt oil or had any smoke issues out the back since I've owned it and so I'm guessing the current prop hasn't caused any real problems, other than when we are in a strong headwind / seas and we can't maintain speed.
__________________
richard_kilburn is offline   Reply With Quote
Old 18-11-2007, 13:28   #28
Marine Service Provider
 
AnchorageGuy's Avatar

Join Date: Mar 2003
Location: Wherever the boat is!
Boat: Marine Trader 34DC
Posts: 4,618
Richard, When we considered re powering we had some interesting conversations with the Perkins folks. First they did not want to be forthcoming with information until I threatened to go on the internet and start looking for folks that wanted to enter into a class action suit. The details are too long and complicated but here are the basics. My Mariner was built by Tayana BTW. The entire engine is not really set up to deliver in the marine environment as Perkins had led us all to believe. The exhaust, according to them should be at least 3" but ours was 2" and there is no way to change that on the engine. So according to Perkins there is a 20% loss in HP right there. The ratings are 50HP at 4000 RPMs however they admitted that this figure was on a bench with no load and it would be impossible to achieve this on our boat no matter what we did. The transmission also entered into the equation as to the ratio, in our case 1.91 to 1. Forgetting the prop at this point with our set up we were developing 27HP at the prop and no way to improve on that with the 4-108. Our max RPMs were 2000 and anything over that would overheat the engine and yes we too were over propped. We almost lost the boat in a gale in the Bahamas because of this and spent a lot of painful hours motoring against currents. The Yanmar has been in since 2001 and there is no comparison to the old performance. It has increased many fold. We new we made the right decision when moving from the mechanics dock back to our slip and we got yelled at for our wake. The engine turns at 3400 RPMs under load with our 17X9 three blade prop.
__________________
Chesapeake Bay, ICW Hampton Roads To Key West, The Gulf Coast, The Bahamas

The Trawler Beach House
Voyages Of Sea Trek
AnchorageGuy is offline   Reply With Quote
Old 18-11-2007, 15:21   #29
Senior Cruiser

Cruisers Forum Supporter

Join Date: Mar 2006
Location: Nevada City. CA
Boat: Sceptre 41
Posts: 3,745
Images: 9
My boat is 21500lbs displacement. I repowered a 4JHE with a 4JH4E. Difference in power is amazing. I have a maxprop. I guess here is another thing to learn How do you know if you are under or over propped. I cruise comfortably at 2500 rpms 7 knots and haven't turned it up so that to see if I can get to the 8 knot hull speed at 3000rpms.
__________________
Fair Winds,

Charlie

Between us there was, as I have already said somewhere, the bond of the sea. Besides holding our hearts together through long periods of separation, it had the effect of making us tolerant of each other's yarns -- and even convictions. Heart of Darkness
Joseph Conrad
Charlie is offline   Reply With Quote
Old 19-11-2007, 10:21   #30
Registered User

Join Date: Nov 2007
Location: Maryland
Boat: Tartan 37C "Windgeist"
Posts: 108
Exclamation Footprint

I scanned the post, if it has already been mentioned oh well...but here goes...

What ever motor you choose, check to make sure the footprint is the same or very similar. The cost of having to rebuild motor mounts and surrounding bulkheads, etc will be big bucks and a lot of headaches.

I would first start by looking for engines that will fit easily in the footprint you already have, then choose from those, if you even have choices
__________________

__________________
Windgeist is offline   Reply With Quote
Reply

Tags
repower

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sabre 28 Repower Iain Engines and Propulsion Systems 10 08-02-2011 13:32
Another New Hello . . . with Questions. Can You Help ? sunangel Meets & Greets 14 28-11-2010 19:08
Engine Repower Advise Schweinsberg Engines and Propulsion Systems 4 30-08-2007 03:39
Repower Catalina 30 with 3GM30F whittem Engines and Propulsion Systems 2 29-07-2007 21:21
Repower? AllyKins Engines and Propulsion Systems 6 06-11-2005 11:32



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 02:58.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.