Repower confusion (horsepower) - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > On Board > Gear & Maintenance > Engines > Diesel
 Not a Member? 


Like Tree13Likes
Reply
 
LinkBack Thread Tools
  #1  
Old 02-02-2013
jrd22's Avatar
Courtney the Dancer
 
Join Date: Nov 2000
Location: San Juan Islands., WA, USA
Posts: 3,844
Thanks: 3
Thanked 18 Times in 18 Posts
Rep Power: 15
jrd22 will become famous soon enough
Repower confusion (horsepower)

Went to the Seattle boat show yesterday to look at a couple of different engine options for a repower and just to see what was new (haven't been for several years). I answered some questions I had(Beta is at the top of my list now), but came away with some new ones regarding how much horsepower I need (or maybe how much I can use is a better way of putting it). The rep for Beta had a nifty program on his computer for determining hp requirements and for our boat he recommended the 38 hp model. The original Volvo we have now is 62 hp. His recommendation is based on the following specs for our boat, prop, etc.
LOA 40'
LWL 35'
Disp 23,000 lbs (26,000 loaded for cruising)
Beam 12'8"
Prop 18" X 12 fixed three blade sail (will probably install 3 blade Max prop)

His program showed that with only an 18' prop there is no way we can use all of the horsepower we have and a 38 hp engine would drive the boat at hull speed at WOT. I would at least go to the 43 hp model because it is a lower rpm engine and jumps up to the heavier duty trans., but even that is a huge drop in hp from what we have now. I like to run things easy, we motor at around 26-700 rpm now (3500 rpm WOT) which gives us a little over 6 knots. The sail prop doesn't give us a lot of thrust, I think we would gain quite a bit of speed with the max prop. The smaller engine would be easier to install, and cheaper, but even 43 hp seems low to me.

So I'm curious, those of you with similar size and displacement boats, what horsepower and prop size do you have, and what speed/rpm do you get out of it? Thanks!
__________________
John
SV Laurie Anne

1988 Brewer 40 Pilothouse

Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 02-03-2013
PorFin's Avatar
Señor Member
 
Join Date: Sep 2007
Posts: 1,340
Thanks: 1
Thanked 8 Times in 8 Posts
Rep Power: 8
PorFin is on a distinguished road
Re: Repower confusion (horsepower)

jrd,

Our boat's got very similar specs as far as LOA/LWL/DISP go, and has a Perky 4.108M installed.

Although the 4.108's rated at 50 hp, that's at max rated RPM (4k) WOT when the stars and planets are precisely aligned; in practical terms we typically run it in the 2200-2400 rpm range for cruising, and with a spanking freshly cleaned hull in dead flat conditions we can go at hull speed (three bladed 16-10 prop). While my memory is fuzzy, I think at those rev's we're looking at around 30 hp output.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
________
'85 BYB Vagabond 39
Reply With Quote Quick reply to this message Share with Facebook
  #3  
Old 02-03-2013
SloopJonB's Avatar
Senior Moment Member
 
Join Date: Jun 2011
Location: West Vancouver B.C.
Posts: 10,930
Thanks: 58
Thanked 56 Times in 53 Posts
Rep Power: 4
SloopJonB will become famous soon enough
Re: Repower confusion (horsepower)

JR, the old rule of thumb of 4 horses per ton would put you at 52 HP in cruising trim.

Of more importance than the horses is the torque and its curve. Are those horses Clydesdales or Quarter horses.

If the torque curve of the Beta gives you adequate grunt at 2800, you really don't need more. The 4 per ton "rule" goes back to the days when sailboats pushed a lot more water out of the way than they do now. My friends Hunter 38 is probably about 20K Lbs in cruising trim with a Yannie in the 30's - it has lots of power at 2800 in that application - we've never needed to run it to 3000 even when bucking our local currents.
__________________
I, myself, personally intend to continue being outspoken and opinionated, intolerant of all fanatics, fools and ignoramuses, deeply suspicious of all those who have "found the answer" and on my bad days, downright rude.
Reply With Quote Quick reply to this message Share with Facebook
  #4  
Old 02-03-2013
Senior Member
 
Join Date: Feb 2010
Location: Narragansett Bay
Posts: 9,478
Thanks: 10
Thanked 158 Times in 144 Posts
Rep Power: 6
Minnewaska will become famous soon enough Minnewaska will become famous soon enough
Re: Repower confusion (horsepower)

You want to have enough power to push the boat to hull speed with oncoming waves at only 75-80 of max rpm. Who would want to run their motor at WOT? Then you want to be able to run an accessory or two, should you choose down the road: spare alternator, engine driven emergency pump, fridge compressor, watermaker pump, etc.

If you have a few extra HPs, you can pull the throttle back and deal with it. If you have too few, you have no options.
oysterman23 likes this.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Jeanneau 54DS

In the harsh marine environment, something is always in need of repair. Margaritas fix everything.
Reply With Quote Quick reply to this message Share with Facebook
  #5  
Old 02-03-2013
jrd22's Avatar
Courtney the Dancer
 
Join Date: Nov 2000
Location: San Juan Islands., WA, USA
Posts: 3,844
Thanks: 3
Thanked 18 Times in 18 Posts
Rep Power: 15
jrd22 will become famous soon enough
Re: Repower confusion (horsepower)

Thanks for the replies, I just assumed that I would replace it with an engine of comparable hp. The program that the Beta guy used went into blade loading, efficiency, etc and it seemed pretty conclusive that even with increased pitch an 18" wheel just couldn't use all that horsepower. Everything else in the drivetrain is overkill too (1.5" shaft, Walter V-drive good for 150 hp, etc.) so I should have figured the engine had more hp than required. If I pull the trigger I think I'll go for the 50 hp model, I'll still be saving a bit of weight and $$, and it should fit back in the "hole" a bit easier too.
__________________
John
SV Laurie Anne

1988 Brewer 40 Pilothouse

Reply With Quote Quick reply to this message Share with Facebook
  #6  
Old 02-04-2013
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 7,050
Thanks: 30
Thanked 57 Times in 53 Posts
Rep Power: 8
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Repower confusion (horsepower)

JR,
Interested in why you are choosing the Beta. Could you rank your choices and give me some f your pro and cons of each in your research.

Dave
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Quick reply to this message Share with Facebook
  #7  
Old 02-04-2013
jrd22's Avatar
Courtney the Dancer
 
Join Date: Nov 2000
Location: San Juan Islands., WA, USA
Posts: 3,844
Thanks: 3
Thanked 18 Times in 18 Posts
Rep Power: 15
jrd22 will become famous soon enough
Re: Repower confusion (horsepower)

Chef- I had it down to a short list of the Beta 60 and the Cummins 3.3 from Transatlantic Diesel (65hp). I also looked into the Yanmar and Volvo but rejected both because they use a turbo and I wanted naturally aspirated (I have nothing against turbos on larger diesels but feel they are an unnecessary complication for small sailboats). I did not look at Westerbeke mainly because of the comments about high parts prices I have read here (I have Volvos, been there, done that), but I'm sure they are good engines and maybe I didn't give them a fair shot. The Cummins is a great engine but Transatlantic is the only place that marinizes them and there aren't too many around. I also talked to a Cummins rep and he questioned whether Cummins would honor the warranty(I think they would) in a marine application (they're an industrial engine) which gave me some doubts. I rejected it because I want to go with something more mainstream.
In my former business I had several pieces of equipment that used Kubota engines and they were reliable and almost impossible to destroy, even though we ran them in the absolute worst conditions imaginable. Beta has a good reputation and people with them seem universally happy with them based on the threads here on SN. I like the fact that they aren't trying to squeeze every last HP out of the engine by using a turbo and intercooler, and that it's a slow rpm engine with a fairly flat torque curve so it should be able to maintain speed into rough weather. I also want to reduce the noise of the engine in the pilothouse and the lower rpm should help a lot with that (the Cummins puts out almost 55 hp at 1800 rpm, which was a big plus in my book). After actually seeing a couple of the Betas at the show I was pretty impressed with how they've done things, it looks simple and I didn't see anything that I didn't like. Beta also offers custom mounts which will make the installation a lot easier (current engine has much wider mounts than most and at two different elevations). I also liked that even though I was set on the 60 HP model the Beta rep spent quite a bit of time convincing me that I didn't need it and could save money by dropping down to the 38 or 43 hp model (big savings for me, much smaller sale for them).
Bottom line, I think almost all of the various engines offered are probably good, you just need to find one that you're comfortable with and doesn't pose too many difficulties changing over from what you currently have.
__________________
John
SV Laurie Anne

1988 Brewer 40 Pilothouse

Reply With Quote Quick reply to this message Share with Facebook
  #8  
Old 02-04-2013
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 7,050
Thanks: 30
Thanked 57 Times in 53 Posts
Rep Power: 8
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Repower confusion (horsepower)

Quote:
Originally Posted by jrd22 View Post
Chef- I had it down to a short list of the Beta 60 and the Cummins 3.3 from Transatlantic Diesel (65hp). I also looked into the Yanmar and Volvo but rejected both because they use a turbo and I wanted naturally aspirated (I have nothing against turbos on larger diesels but feel they are an unnecessary complication for small sailboats). I did not look at Westerbeke mainly because of the comments about high parts prices I have read here (I have Volvos, been there, done that), but I'm sure they are good engines and maybe I didn't give them a fair shot. The Cummins is a great engine but Transatlantic is the only place that marinizes them and there aren't too many around. I also talked to a Cummins rep and he questioned whether Cummins would honor the warranty(I think they would) in a marine application (they're an industrial engine) which gave me some doubts. I rejected it because I want to go with something more mainstream.
In my former business I had several pieces of equipment that used Kubota engines and they were reliable and almost impossible to destroy, even though we ran them in the absolute worst conditions imaginable. Beta has a good reputation and people with them seem universally happy with them based on the threads here on SN. I like the fact that they aren't trying to squeeze every last HP out of the engine by using a turbo and intercooler, and that it's a slow rpm engine with a fairly flat torque curve so it should be able to maintain speed into rough weather. I also want to reduce the noise of the engine in the pilothouse and the lower rpm should help a lot with that (the Cummins puts out almost 55 hp at 1800 rpm, which was a big plus in my book). After actually seeing a couple of the Betas at the show I was pretty impressed with how they've done things, it looks simple and I didn't see anything that I didn't like. Beta also offers custom mounts which will make the installation a lot easier (current engine has much wider mounts than most and at two different elevations). I also liked that even though I was set on the 60 HP model the Beta rep spent quite a bit of time convincing me that I didn't need it and could save money by dropping down to the 38 or 43 hp model (big savings for me, much smaller sale for them).
Bottom line, I think almost all of the various engines offered are probably good, you just need to find one that you're comfortable with and doesn't pose too many difficulties changing over from what you currently have.
Thanks for the reply. I think that Beta is a good engine. I have a friend whoi is a SN who just installed one. I agree with you phiosophy about the turbo. I feel the same way about an extra thing to complicate it. And volvos are just to expensive to repair.

I guess the reason I asked though is that I prefer the Yanmars slightly. For many of the same reasons you enumerated plus the Yanmar was not a converted engine and was built originally as a marine engine

I thought the 53 Hp Yanmar 4JH54 was a normally aspirated one and that it was the 73 HP 4JHTE was turbo charged.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Quick reply to this message Share with Facebook
  #9  
Old 02-04-2013
Senior Member
 
Join Date: Feb 2010
Location: Narragansett Bay
Posts: 9,478
Thanks: 10
Thanked 158 Times in 144 Posts
Rep Power: 6
Minnewaska will become famous soon enough Minnewaska will become famous soon enough
Re: Repower confusion (horsepower)

I agree, turbo chargers on sailboat diesels are evil. Some argue they are more fuel efficient at comparable HPs, but no doubt in my mind you will give it all back in turbo maintenance over time. I can only see them as useful, if you just don't have the room to hold the block of the size motor you need to push your boat as you like. This is a bigger problem with stinkpotters than sailboats.

I do not believe the entire line of Yanmars and Volvos are turbo charged.

One other thing to consider is the resale value of your boat. It seems the ubiquitous motor in the US these days is the Yanmar. I don't think its superior, but it seems to be the brand whose parts are most commonly stocked and the first certification the local yard wrenches get. If true, that makes it the easiest to deal with.

The idea that a diesel has been marinized from a common block is appealing, if you can buy non-marine parts or disposables. However, you have to be wary that you are not de-marinizing it in the process and are knowledgeable of the difference. How will the next owner feel about it.

Just some food for thought.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Jeanneau 54DS

In the harsh marine environment, something is always in need of repair. Margaritas fix everything.
Reply With Quote Quick reply to this message Share with Facebook
  #10  
Old 02-04-2013
chucklesR's Avatar
Senior Member
 
Join Date: Sep 2007
Location: Pasadena Md - Magothy side
Posts: 5,979
Thanks: 10
Thanked 31 Times in 31 Posts
Rep Power: 10
chucklesR is a jewel in the rough chucklesR is a jewel in the rough chucklesR is a jewel in the rough
Re: Repower confusion (horsepower)

If you have the $$ go bigger, as said before you'll be wanting a little extra for altenator/watermaker/yada yada's that will be taking HP directly off the top (before it gets to the prop).

I'm surprised the software indicated only a 38 to swing the 18x2 x 3, but you don't mention the transmission and the reduction ratio so that's hard to figure.

It's a tad to early in the morning for me to reverse engineer the math on the amount of HP required to swing that diameter at 12 pitch to your hull speed.
I'm no naval architect, didn't stay at a hotel of any type last night etc.. but:

My dinky little Irwin 38 at 20k runs with a 44hp

Putting a smaller motor on bigger and heavier seems like underpowered to me.
__________________
Lessons learned are opportunities earned.
Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fiberglass Confusion SailingAlien Gear & Maintenance 4 05-29-2009 01:36 PM
Link 20 confusion. chris_gee Gear & Maintenance 3 01-28-2009 02:57 AM
Horsepower to Displacement? dhornsey Gear & Maintenance 32 03-23-2008 08:53 PM
Horsepower - Gas vs. Diesel TSteele65 Gear & Maintenance 36 07-14-2007 07:51 PM
Alberg 30; horsepower? greencaptn Boat Review and Purchase Forum 3 01-31-2007 11:25 AM


All times are GMT -4. The time now is 06:02 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.