I have a 1981 H30 that will not reverse to starboard. From reviews of that model on this site, the inabillity to reverse to starboard appears to be a characteristic of that model. I have no idea why it won't do it, but it won't. Is it possible to fix this problem without drastic changes to the hull, keel, or rudder?
Reverse to starboard?
- Thread starter AndyO
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Simple answer, NO.
Prop walk is always to port on a right hand turning prop. Learn to use it to your davantage.
Prop walk is always to port on a right hand turning prop. Learn to use it to your davantage.
Re: Simple answer, NO.
I have a 1980 H36. I've posted several times about the same problem. When I engage reverse with the boat stopped, the prop wash exits the boat almost perpendicular to the fore/aft axis. So the first motion of the boat is that the aft swings hard to port before any backward motion is acheived. Most people say (without guarantee) that a 3 blade prop will help. But I don't know yet. I'm waiting until my next haulout to install one. The existing prop 2 blade prop I think is original issue and has minor pitting in a few spots, so probably time to change out anyway. It's diameter is 16". Clearance between the hull and the prop is only 1.5". Less than normal. This may account for some of the prop walk issues. Changing to a 3 blade can be smaller diameter = more blade/hull clearance. Yes, I know that one can learn to use prop walk to good advantage. But in my boat's case, its too much of a good thing!
I have a 1980 H36. I've posted several times about the same problem. When I engage reverse with the boat stopped, the prop wash exits the boat almost perpendicular to the fore/aft axis. So the first motion of the boat is that the aft swings hard to port before any backward motion is acheived. Most people say (without guarantee) that a 3 blade prop will help. But I don't know yet. I'm waiting until my next haulout to install one. The existing prop 2 blade prop I think is original issue and has minor pitting in a few spots, so probably time to change out anyway. It's diameter is 16". Clearance between the hull and the prop is only 1.5". Less than normal. This may account for some of the prop walk issues. Changing to a 3 blade can be smaller diameter = more blade/hull clearance. Yes, I know that one can learn to use prop walk to good advantage. But in my boat's case, its too much of a good thing!
Like the others said, it's prop walk, and you can learn how to use it. I thought the same thing about my '82 H30 at first. Then I read the chapter in Chapman Piloting Seamanship and Small Boat Handling on boat handling under power and it made sense. I am now able to reverse to starboard under most conditions and I still have the standard two-blade prop. Get yourself a copy of that book (Even a used one. The principles have not changed. Mine was published in '79.) and study that Chapter. It's the most comprehensive explanation of prop walk that I have seen.
Good luck. It takes some practice, but armed with knowledge of how and why the boat responds the way it does, you'll get the hang of it in no time.
Good luck. It takes some practice, but armed with knowledge of how and why the boat responds the way it does, you'll get the hang of it in no time.
Left hand prop!
You may want to consider contacting a good prop shop for some advice. Lack of tip clearance can also make the problem worse.
I assume that you have the 1 cyl yanmar.
You may want to consider contacting a good prop shop for some advice. Lack of tip clearance can also make the problem worse.
I assume that you have the 1 cyl yanmar.
You are obviously serious about this and if you just cannot live with it then why not try a significantly smaller prop. Say come down 1.5" in diameter and perhaps increase the pitch.
Obviously your motoring performance will be compromised but if it works then a more permanent solution may be somewhere in between.
The 'normal' clearance between prop tip and hull is said to be 15% of diameter for 'acceptable' prop walk.
A good prop shop should lend you a suitable prop for a short while if you intend to purchase from them if successful.
Obviously your motoring performance will be compromised but if it works then a more permanent solution may be somewhere in between.
The 'normal' clearance between prop tip and hull is said to be 15% of diameter for 'acceptable' prop walk.
A good prop shop should lend you a suitable prop for a short while if you intend to purchase from them if successful.
I had read of prop walk but had no idea it could be this severe. Mine behaves exactly as Rardi describes above.
An old edition of Chapman's came with the boat, so I'll start reading there. If that doesn't help, I may try a different prop as Donalex suggests.
This is a great forum. Thank you all for your advice.
An old edition of Chapman's came with the boat, so I'll start reading there. If that doesn't help, I may try a different prop as Donalex suggests.
This is a great forum. Thank you all for your advice.
Dear Capnjeffw:
Yes, the thought about modifying the skeg section of the hull had occurred. But discarded because:
- Lot of work...and probably beyond capability of even a try-just-about-anything DIY'er (that would be me).
- Probably very expensive.
- Lots of things are happening in the area such as cutlass bearing, prop shaft exiting the hull, and rudder post. (Attached is a pic of the stern section of the hull I had from the purchase survey -- sorry about the quality). And there would be concerns about affect on general structural strength of the hull. Would need the services of a yacht engineer?
- Would the mod adversely affect the handling characteristics under sail power?
- Wouldn’t be 100% certain that the modification will make a major difference… so would be an expensive experiment.
Summary: The cost/benefit trade-off favors continued coping with the pronounced prop walk until trying the cheaper/easier alternative of a smaller diameter and 3-blade prop to be installed when I next haul out. If that doesn't help, then I'll just need to get better at dealing with this boat's severe prop walk.
rardi
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Rardi:
I would suggest that you contact Kilian Prop in Alameda. They have a process that they put winglets on your prop. This process is said to give the prop more bite and will also hellp the prop walk. This can save you a load of money over purchasing a new prop.
What motor do you have in your boat?
I would suggest that you contact Kilian Prop in Alameda. They have a process that they put winglets on your prop. This process is said to give the prop more bite and will also hellp the prop walk. This can save you a load of money over purchasing a new prop.
What motor do you have in your boat?
Your prop, strut, and rudder appear identical to my H37C. And it looks like plenty of clearance but as you state, not a real good picture. I also had the 2QM20 when I switched to a 2-blade Flex-O-Fold which significantly reduced prop walk. You can call them and discuss why it works so well. Now with my new 3YM30 and 3-blade Flex-O-Fold I have even less. Still if I run it up to 3000 rpm it will start to creep to port. So I goose it, go to neutral, and then she will follow the rudder. I still have the 2-blade somewhere. Also have the 14x14 3-blade that I bought when I lost the new one in the Erie Canal. I have to tell you there is a tremendous difference with the folder, both motoring and sailing.
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I had the Killian non slip tips put on my 15X12 5 years ago. I dont really find a lot of difference in backing in terms of prop walk. Maybe a bit straighter after the boat gains way but still goes right when stopping.
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