Being a the new owner of Condor P27 121 I am looking for some information around propeller sizes. Just collecting information/ideas before the end of season when I can get Condor out of the water and make any adjustments.

Currently max speed is only 4knots - the engine (Yanmar 1GM10)does not get to full revs and there is a lot of black smoke and pick up form neutral is very slow. All symptomatic of being over pitched.

Can anyone with the same engine let me know how their boat performs, the propeller size and gearbox type. In this way I can be armed with some information before speaking to a propeller supplier.

At the moment I do not know the size of prop. I have fitted - (it is a 3 blade fixed) and I have not recorded the gearbox type however if I can collect some data form other owners I should be able to make an informed judgement and see what the experts say. If anyone knows of a firm which can also advise their contact details would be useful.

Any information appreciated

Andy

Andy,

My P27 No. 147 has a 2 blade folding Gori prop; size 14 * 9.5 RH which works fine with my 28 year old Yanmar 1GM10. My gearbox is the KM2P variant.

On a flat sea when newly anti fouled I can achieve 6.5 knots flat out, but this is wasteful of fuel and I find it is better to cruise at half to 2/3 throttle and achieve 4-5.5kts.

Andy

My prop is not really comparable to yours, I have a 26 but engine is a Beta 14 twin.

My prop is a Flexofold 14x11. Flat water cruising at 5.5-6.0knots at about 3/4 throttle, no smoke.

The main reason for this post is to let you know about Darglo Marine Engineers from Wareham, I took them my prop to check.

They inspected and balance tested the prop and checked that it was the right one for my boat/engine/gearbox (which it was).

Their advice was take it back and put it back on the boat! No charge!

Philip superseal rascal 50

Martin, Philip,

Thanks for the replies - useful info.. As I have a 3 bladed prop this points more and more to the prop and engine not being matched. I had been recommended Darglo by a friend so I will be talking to them in over the winter.

Hi Andy

Just seen your post, I have a P27 which I re-engined with a 2GM20 but when it had a 1GM10 with a 2.6:1 gearbox, it went fine with a three bladed 14x8 prop, which I still have if you're interested in trying it. I live in West Sussex, it has a 12:1 taper and 1/4" keyway. Needs a bit of a clean up from sitting in my garage these last four years.

Martin Watson, P27 Frith.

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Hi Andy

When I had my first Parker, a 275 , Bright Eyes, I had terrible engine problems , lots of black smoke and rough running, in fact all the symptoms of overload or worse. In the end I found the problem was an "Uprated" alternator. The GM 10 is not capable of the torque required for the 55amp alterator under full load. Note this would not be observed unless the batteries needed full charge. Hopefully this is not your problem but if it is , it is easy to sort with the boat still in the water.

Just fit a standard 35 amp alternator.

Jan Newman

325/32

Blue Moon

I would be very careful about putting a smaller alternator on if that is the problem, unless you are a competent electrician and understand the relationship between you ships battery total capacity and your alternator. It is strongly recommended that your alternator should be rated at between 25% and 33% of your total battery capacity, otherwise you will either risk cooking the batteries if the rating is above this ( I know the regulator should protect against this but it is all supposed to be part of a balanced system), or you will never fully charge your batteries if below this rating and in so doing significantly shorten your battery life. The standard alternator on the 1GM10 and 2GM20 is a 35A alternator with the option of a 55A alternator for the 2GM20. If a 55A alternator has been fitted to a 1GM10 it is highly likely that a larger battery bank has been installed. The standard alternator pulls about 3/4Hp out of the engine and the 55A alternator pulls about 1 1/2Hp, which is quite significant on an engine only developing 8Hp from new and probably only delivering 6~7Hp now. It's the reason I changed up to a 2GM20 on my P27 because I fitted a larger battery bank (170Ahr house battery and 55Ahr starting battery)and a 65A alternator to feed my compressor coolbox without the need for dock power I also have over 100Wh solar panels feeding the batteries during sunlight and am completely independent of the need for shore power or engine running to keep my batteries topped up so long as there is decent sunlight.

For more information I recommend reading Nigel Calders book, Boatowner's Mechanical and Electrical Manual (about £40 new but available from the library) it is an absolute treasure trove of information and is considered by most as the boatowners Bible.There is even a section on propellor selection.

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