Hi, I’ve just finished your latest Storm Tactics, it’s grate.I’ve also read and loved your others. Can you tell me how to tell if my prop is sized properly.I own and am planing on cruising my Rob Perry designed Islander 32. It has a Westerbeak 25 hrs . My engine manual doesn’t say anything about max engine RPM. My current prop is a 12/14 two blade. At full throttel the RPM is 3400. I’m not sure what my hull speed should be,the waterline is 25′, and I can’t look it up in my Cruisers Encyclopedia because I lent it out and havent gotten it back.I can get .4 gal per hour and about 5kts at 1800 RPM. Is this too low of a power setting for long periods. Do deisel do better at higher settings. Is it hard on them to run at higher settings, say 3000 RPMs for extended periods.It seems that power settings above 2600 dont produce higher boat speeds.Any thaught on all the above would be a great help. Thanks
Following you’ll find lots of questions and answers related to propellors.
If you’ve got a question that you don’t see here, click on “Cruisers Q&A” in the sidebar, and use the form to send in your question.
Question: I was going to install a feathing prop on my Nautic Saintongue 44 during this spring’s haul-out. Presently, I have postponed this investment because I met a couple in La Paz this winter who had a feathering prop on a Passport about the same displacement as my boat. I asked them if the prop (maxi) was working for them. They replied that if they had to consider it again, they would not do it again. Basicially it was not worth the investment.
So, what is your opinion on replacing a fixed three blade with a maxi type prop? From manufacturers reports I have read, an increase in speed will be realized, but on a 25,000 lb. displacement boat, is the investment worth it? I do not race, but like to get from one place to the next as quickly as possible.
What prop has worked best for your boats over the years? Mike
I replaced my fixed prop ( 3-blade 16 RH 10) with a 17 RH 10 Flex-O-Fold 2-blade folding prop. I have experienced much improved speed under sail and not bad performance in reverse. However, I am unable to get full cruising RPM in forward and because of this am not able to motor cruise at much more than 4.3 knots. My vessel is a Nautilus 37 with a 35 hp Yanmar diesel. Also I am experiencing vibration at 1900 RPM which I did not have with my fixed prop. Any suggestions? Ron
Hi again. We are in the process of installing a diesel engine in our Mirage. All was going according to plan, until a fellow boater mentioned crabbing, and warned us that placement of the prop is critical. If not offset, the boat will ‘crab’, worse in reverse, than in forward. Next Saturday, the hole is being cut through the hull. I’ve had a look through the Encyclopedia, but can’t find much about proper placement of the shaft/prop, and although many of my boating friends have heard of it, no one can elaborate. I’ve looked at the last few boats in the area that are still out of the water, and find that the shaft is placed dead-centre. Do you have any advice, or do you have a publication that explains the concept? Your help is appreciated. Jim from Canada
I am thinking of changing my fixed three-bladed prop for something that causes less drag. The Autoprop from Brunton’s Propellers seems very interesting. What do you know about it? P.S. Your Encyclopedia is a fantastic source of knowledge!
I am building a Bruce Roberts kit of 54′ radius chine cutter. After reading the Offshore Cruising Encyclopedia and viewing your Beowulf: The Legend DVD, I have decided to install CP prop by Hundested. I am getting the prop from Todd Terry at Pacific Marine Equipment, Inc. in Seattle. As far as I was able to find out, they are the (US) West Coast distributor for Hundested gear. Anyway, the thing is: You are saying in your book that you were using VP2 model, which according to Todd is no longer available. Therefore I am going with a bit larger VP3 model. Now, according to Todd, one can choose either fully reversible pitch prop or fully featherable prop to minimize the drag while sailing.
If I choose fully featherable prop, my reverse pitch is very minimal, nowhere near the forward pitch. If I choose the fully reversible prop I will have to give up the low drag feature of fully feathered prop.
After viewing Beowulf DVD In the chapter titled "Maneuvering Under Power", you have Linda reverse the pitch from 3.5 ahead to 4 astern. The scale on the gauge shows up to 6 ahead, up to 5 astern and also feathered position. Does it mean that with the VP2 you had the option of having nearly fully reversible pitch and also feathered position for sailing???
Are you familiar with the VP3 model and what is the difference between it and the old VP2 one? I have seen the operational model of VP3 in Seattle and in fact the reverse pitch is very minimal, a fraction of the forward pitch capabilities. Was your prop the same way?
I am sorry for rumbling on and on about it, but the Hundested props as you know are not cheap and I would like to make sure that my money will be wisely spent. I would be very grateful for your comments regarding this matter.
Good luck with your UnSailboat! I hope to meet you one day in some anchorage. Best Regards, Remek
What kind of prop do you use on BEOWULF and is it a feathering prop or folding? I know that you do motor sail and I wonder how you came to the size and pitch that you needed for the boat. I also liked the Bermuda story about the weather, you made a very good move by moving to a new location, it could have been a bad situation had you not moved. Good Sailing, Gary H
Hi! My dealer and I are having this contest, you know the kind 😉 about painting the prop shaft and prop. He’s already done it, and insists it’s "always done that way." I say no. I want the paint removed. The vessel is a 2000 Hunter Passage 450, the prop is an Autoprop. The Autoprop dealer (A&B Marine) recommends not painting but using their "Anti-Fouling Goop," a greasy lanolin compound. I have had to scrape the barnacles off the prop personally, so I know that bottom paint does not retard marine growth here in SW Florida. The Goop "seems" to work. It’s not been tried on a clean prop over an entire season. Comments? I love the books, videos, CDs and am amazed with MaxSea, especially the weather routing. Keep sailing! Errrr…… Boating!!!!!! Regards, Drew D
Steve… I have your Offshore Cruising Encyclopedia and I have almost finished building this 35′ steel sail boat. I’m having a little trouble sizing the prop…Boat is 9.5 tons…engine is Farymann 32 HP…Prop is 16×13, 3 blade… Max. RPM under no load conditions is 2400. Max. RPM in forward is 2100 at max hull speed of 7.5 kn…reduction of transmission is 2:1. Should the max. R’sPM under load be closer to 2400?… Should top speed be reached before 2100?… I hope you can help with this … Thanks–Basil
What effect is there on propeller performance and vibration when fitted in the opposite rotation to that recommended by the boat builder?
I just purchased a 9 year old Grand Soleil Maxi One (19.5m) and am having a lot of problems with engine & MaxProp giving a lot of very bad vibrations and engine not being able to obtain correct cruising revs (should be about 2700/2800 rpm–and getting black smoke when revving above 2200rpm).
Obvious answer is the prop is over pitched. However, on checking with MaxProp rep here in Athens, he just serviced and refitted the prop with 20 degs with right rotation. According to the Manual on board from the builders (Canteir del Pardo) the prop should be 14 degs–Left Rotation.
Of course the over pitching of the prop answers the problem of the engine not revving etc, but would the wrong rotation cause increasingly bad vibrations the more rpm’s applied?
I need some urgent advice because the incorrect running of the engine over the last 8/9 years (by previous owner) has caused all sorts of problems including overheating, broken pipe in heat exchanger and blown gasket leading to water into the cylinders and turbo etc on my recent outing with service engineers on board testing the engine after service. Thus, decided to put new engine as do not want to have further trouble/time/expense of trying to renew/overhaul existing engine.
Obviously have to find also a solution for the bad vibrations, but I cannot get Maxprop or del Pardo to reply to my emails and faxes.
I wonder if you have any opinion on electric propulsion? I am considering re-powering with a Solomon system. I have a 30hp Westerbeke diesel at this point. I am cruising full time with lots of hours at anchor. Comparing prices, diesel/electric, is a definite apples/oranges situation, with the result being that I may decide based on my dislike of the internal combustion engine. Certainly would appreciate your reaction to the this concept used in a cruising sailboat. Ross
I very much enjoyed your Encyclopedias, Volumes 1 and 2…Do you have an address for the manufacturer of the Paul Luke "Hyde" propellers? I have used several Barrett and Maxiprops over the years, and have found them to be VERY inefficient compared to a fixed pitch (like 2.5 knots worth) It always seemed to me that a feathering prop with a little twist would be the answer, but I didn’t know that they existed until I saw reference to it in your book. If it’s not too much problem, do you also have a source for your "Murphy" gauges?
Dear Steve, I have a Kelly Peterson 46 with a fixed 3-blade prop. I want to change it to a feathering prop. I am intrigued by the continuously adjusting Autoprop which is supposed to match pitch to engine rpm and twist more or less flat to cut drag under sail to 85% of a fixed blade prop. I wonder what happens to the independently adjusting blades when barnacles form and they become unbalanced. Maxprop has less drag under sail but its pitch is optimized for max rpm and falls off (like fixed props) at lower engine rpm. Do you know how well these things work in the field? Any kudos or horror stories. Thanks, Carl
Steve, I was fortunate to have sailed with you and Linda in Ventura a number of years ago and got to back your boat into the slip easily due to the max-prop. I need to decide between a max-prop and a controllable pitch prop. It seems that the max-prop might have the advantage in backing where the cpp shines due to ease of adjustment underway. Which do you prefer and why? Robert
Hi Dashews, Have 3 of your great books and getting a great deal from them. My yacht has a free-wheeling engine shaft and I understand someone has developed a system whereby you can mount an electrical generator inside the boat to the engine shaft via a belt and a set of pulleys–have you any information on this system, or contacts where it could be obtained? Regards, Mike
In your very valuable Encyclopedia (looking forward to read the heavy weather issue) you briefly mentioned a way to generate DC power with a MAXPROP or AUTOPROP. Is there any description available on this setup? My boat is a Gerard Dijkstra designed 77 ft centerboard shooner (steel, 60 tons) and a MAXPROP is fitted but I am thinking of changing to AUTOPROP (only for performance when maneuvering). Is it possible to do the same trick with this prop? I hope you find the time for an answer. Best regards, Paul