Folding prop help - Page 3 - SailNet Community
 1Likes
Reply
 
LinkBack Thread Tools
post #21 of 37 Old 11-21-2012
Junior member, rest old
 
msmith10's Avatar
 
Join Date: Feb 2009
Location: Columbus Ohio
Posts: 497
Thanks: 3
Thanked 0 Times in 0 Posts
Rep Power: 7
 
Re: Folding prop help

I doubt if you're underpowered. How fast (RPMs) can you get the engine going in gear? You want to be running at a higher RPM to get up the torque curve.
The Atomic 4 was the most common engine in C&C30s until about 1979-1980 when they stopped production. The A4, although rated at 30 hp, would max out at about 2200 rpm with most props, and was only generating about 12-15 hp at that speed, but that is plenty of power.
If you're not going to race, you don't need a folder. As Rob said above, a 3 blade would be the way I'd go if I didn't race.

Mark Smith
1977 C&C 30 Mk 1 hailing from Port Clinton, Ohio
msmith10 is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #22 of 37 Old 11-22-2012 Thread Starter
First String
 
Join Date: Jan 2009
Location: South carolina
Posts: 859
Thanks: 45
Thanked 9 Times in 9 Posts
Rep Power: 7
 
Re: Folding prop help

Yanmar's 2GM has provided almost 30 years of reliable operation, reports Andrew Norton

Released in the late 70s, the Yanmar 2GM was the forerunner of the 2GM20 and developed 13hp (based on 1.0hp equaling 746W) at 3300rpm with a maximum continuous rating of 11.8hp at 3200rpm. The RPM's my boat likes is 2200 rpm's and will not idle up much faster? It will not go to 3300? It has 30 years on the engine without an hour meter. I have no way of knowing how many hours it may have. It dont burn oil. That being said could it be the prop? or are the expections for this little prop and 11.8 HP engine set a little on the high side?


ltgoshen is offline  
Quote Quick Reply Share with Facebook
post #23 of 37 Old 11-22-2012
HANUMAN
 
RobGallagher's Avatar
 
Join Date: Aug 2001
Location: Noank, Connecticut, USA
Posts: 1,503
Thanks: 7
Thanked 28 Times in 27 Posts
Rep Power: 14
 
Re: Folding prop help

Quote:
Originally Posted by ltgoshen View Post
Yanmar's 2GM has provided almost 30 years of reliable operation, reports Andrew Norton

Released in the late 70s, the Yanmar 2GM was the forerunner of the 2GM20 and developed 13hp (based on 1.0hp equaling 746W) at 3300rpm with a maximum continuous rating of 11.8hp at 3200rpm. The RPM's my boat likes is 2200 rpm's and will not idle up much faster? It will not go to 3300? It has 30 years on the engine without an hour meter. I have no way of knowing how many hours it may have. It dont burn oil. That being said could it be the prop? or are the expections for this little prop and 11.8 HP engine set a little on the high side?


How about in neutral?

1. Test it with another tachometer.
2. If you are not getting enough RPM it's time to do some trouble shooting. Could be anything from the linkage/throttle to fuel to exhaust.

Do some research, make a list of possibilities and start checking them off.
msmith10 likes this.
RobGallagher is offline  
Quote Quick Reply Share with Facebook
post #24 of 37 Old 11-22-2012
Closet Powerboater
 
MedSailor's Avatar
 
Join Date: Mar 2008
Location: Anacortes PNW
Posts: 3,546
Thanks: 254
Thanked 110 Times in 100 Posts
Rep Power: 8
 
Re: Folding prop help

Is the prop clean? A neighbor of mine could only do 2.7 knots on a calm sea at full throttle with the new boat he bought. One dive later, he was doing 7.5knots at 2400RPM.

Check and make sure the prop is clean before making any drastic spending decisions. Even a few barnacles on the prop can make a HUGE difference.

MedSailor

I have a sauna on my boat, therefore I win.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Last edited by MedSailor; 11-22-2012 at 01:12 AM.
MedSailor is offline  
Quote Quick Reply Share with Facebook
post #25 of 37 Old 11-22-2012 Thread Starter
First String
 
Join Date: Jan 2009
Location: South carolina
Posts: 859
Thanks: 45
Thanked 9 Times in 9 Posts
Rep Power: 7
 
Re: Folding prop help

Quote:
Originally Posted by MedSailor View Post

Check and make sure the prop is clean before making any drastic spending decisions. Even a few barnacles can make a HUGE difference.

MedSailor
I had it hauled in the spring it was the 16th of march that we splashed it. It was like this the whole time I have owned it. I know it is clean I have paid a diver 5 times this summer to clean it.
ltgoshen is offline  
Quote Quick Reply Share with Facebook
post #26 of 37 Old 11-22-2012 Thread Starter
First String
 
Join Date: Jan 2009
Location: South carolina
Posts: 859
Thanks: 45
Thanked 9 Times in 9 Posts
Rep Power: 7
 
Re: Folding prop help

Quote:
Originally Posted by RobGallagher View Post
How about in neutral?

1. Test it with another tachometer.
2. If you are not getting enough RPM it's time to do some trouble shooting. Could be anything from the linkage/throttle to fuel to exhaust.

Do some research, make a list of possibilities and start checking them off.
It will rev higher in neutral. I donít have a spare tec? That would coast quite a bit for a test procedure. I think I will spend some time this winter jacking it up a bit. Thanks for the help
ltgoshen is offline  
Quote Quick Reply Share with Facebook
post #27 of 37 Old 11-24-2012
Senior Member
 
Join Date: Aug 2008
Posts: 338
Thanks: 2
Thanked 4 Times in 3 Posts
Rep Power: 7
 
Re: Folding prop help

I have a C&C 29-2 with a 2gm and Martec folder. I cruise at 2800 RPM all day at 6.3 knots. ( In fact, I ran it for 22 hours straight going to Mackinac in 2010 when there was no wind. The 2GM is a jewel when properly maintained) The 29-2 is a bit lighter but I would imagine you should motor at about 6 knots with the proper sized and functioning Martec. I had mine reconditioned by Martec last year for about $250 which was a worthwhile investment.
Sanduskysailor is offline  
Quote Quick Reply Share with Facebook
post #28 of 37 Old 11-24-2012
Member
 
Join Date: Mar 2010
Location: SF - South Bay
Posts: 579
Thanks: 1
Thanked 21 Times in 21 Posts
Rep Power: 6
 
Re: Folding prop help

As has been pointed out by others, and worth reiterating: Consider how you will use the boat.

If you want to race, and have the money, get a folding prop as discussed. No-brainer.

If you are cruising/weekend sailing, consider a fixed prop - for a boat your size, a 3-blade. Fixed props are significantly cheaper (there is a big used market), easier to maintain, less likely to go wrong if you are miles offshore. Arguably more robust. Arguably better for reversing - although much depends on the folder brand.

Folding/feathering props are more expensive, benefit from maintenance (e.g. annual removal, cleaning, reassembly), more likely to go wrong - BUT you'll probably get 0.5knot more speed, and they tend to be quieter (although fixed props people often leave the engine in reverse - no noise, more drag).

Good luck!
paul323 is offline  
Quote Quick Reply Share with Facebook
post #29 of 37 Old 11-24-2012
Senior Member
 
blt2ski's Avatar
 
Join Date: May 2005
Posts: 6,862
Thanks: 0
Thanked 26 Times in 25 Posts
Rep Power: 12
   
Re: Folding prop help

Fixed vs folding/feathering is a big subject, kinda like which anchor to use! Generally speaking, you can get upwards of .5-.75 knots in many wind conditions with a folding/feathering prop, so that will keep you sailing vs motoring in lighter winds. SOME of the feathering props, like the max prop, have better reverse than a fixed prop! along with very little prop walk! and will be around 90-95% forward of a fixed prop.

BUT, as noted, fixed props will be less money.

My boat at 6500-7000 lbs moves just fine with a 14x7" 2 blade max prop, I can do 6knots all day at .5 gals and hr. Something as mentioned, could be wrong with the blade itself.

Many cruisers, like feathering/folding props better than fixed. A 3 blade as mentioned, will have more bite, due to a higher surface area. a 4 blade even better yet to a degree. I would go with a 3 blade if I had to replace my max prop. It would be a max prop or some other equal.

Marty

She drives me boat,
I drives me dinghy!
blt2ski is offline  
Quote Quick Reply Share with Facebook
post #30 of 37 Old 11-24-2012
Closet Powerboater
 
MedSailor's Avatar
 
Join Date: Mar 2008
Location: Anacortes PNW
Posts: 3,546
Thanks: 254
Thanked 110 Times in 100 Posts
Rep Power: 8
 
Re: Folding prop help

Quote:
Originally Posted by paul323 View Post
As has been pointed out by others, and worth reiterating: Consider how you will use the boat.

If you want to race, and have the money, get a folding prop as discussed. No-brainer.

If you are cruising/weekend sailing, consider a fixed prop - for a boat your size, a 3-blade. Fixed props are significantly cheaper (there is a big used market), easier to maintain, less likely to go wrong if you are miles offshore. Arguably more robust. Arguably better for reversing - although much depends on the folder brand.

Folding/feathering props are more expensive, benefit from maintenance (e.g. annual removal, cleaning, reassembly), more likely to go wrong - BUT you'll probably get 0.5knot more speed, and they tend to be quieter (although fixed props people often leave the engine in reverse - no noise, more drag).

Good luck!
Very well put. I agree totally with what paul has said. I would also like to mention that many are very happy with the "low drag fixed 3 blade prop" made by Campbell. Practical sailor has surely done a review somewhere as well. If I had extra money, this is what I would get as I prize reliability over drag, but would like to reduce drag.
West by North Enterprises - Campbell Sailer


If you like folders there is a fairly inexpensive folder on the market with replacable carbon fiber blades called the kiwiprop.
Kiwiprop Home of the Kiwi feathering prop

MedSailor

I have a sauna on my boat, therefore I win.
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
MedSailor is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

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:
OR

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
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
folding prop help Ifishli Gear & Maintenance 5 06-26-2009 10:07 AM
best folding prop? e31 Gear & Maintenance 11 11-15-2003 08:13 AM
folding prop chris1514 Racing 7 09-19-2003 10:43 PM
used folding prop chris1514 Racing 0 03-13-2003 05:47 AM
folding prop chris1514 Gear & Maintenance 0 03-13-2003 05:44 AM

Posting Rules  
You may post new threads
You may 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 On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome