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Message board > Engines > Suzuki 70hp 4 stroke Prop Size

Message 22 of 22
Posted by member Ian Martin on Monday 17 October 2005

Hi Andy - Steve Thanks for your comments: Andy to address your comment on tabs being fully deployed at 20 Knots at the time I was trialling the new configuration on the Pilot. Having spoken with Hardy regarding hull speed, design i.e. semi displacement, the hull is not planning or semi planning, I do not power my vessel at 20 Knots since that day. The hull is not designed for speeds of 20 knots plus. The tabs are used as per sea conditions and load distribution in the vessel. I have trialled the vessel with various load configurations and load shift i.e. my two teenagers (average weight and height) moving from the cabin to the aft end of the vessel or the vessel is listing to one side due to weight I would adjust the trim tabs accordingly to compensate. Steve I have noticed that when I fully retract the tabs the bow still tends to lift, I retract the tabs around 1/3 up, about 2 clicks I have the digital indicator/adjuster fitted, and the vessel motors along without any problem 14.5/15 knots. Again it depends on the load I'm carrying and the sea conditions at the time. I use the tabs enough to get me on the the horizontal and reduce any drag. I would still feel uncomfortable pushing the vessel at 20 knots plus due to the hull design. I have owned various configurations of vessels in the past 30 years and find the Hardy Pilot a very comfortable, sturdy and sea worthy vessel used in the right conditions.

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Message 21 of 22
Posted by member Steve Streets on Saturday 15 October 2005

Ian, This may help or not, but I only use the trim tabs fitted to my Hardy Pilot to get it on the plane under acceleration. Once on the plane I retract the trim tabs.

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Message 20 of 22
Posted by member Andy Mcmullan on Friday 14 October 2005

Hi Ian I noticed in your post that you were running your pilot with your tabs 'fully deployed' and the boat didn't feel right at 20 or so knots. I was wondering why you had them fully deployed at this speed? I thought that full deployment was only necessary on acceleration to reach planning speed. Cheers Andy McMullan

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Message 19 of 22
Posted by member Defay Jean-Louis on Friday 5 August 2005

Hi Angus Geaddes Thank you for your message j could get 17 knots at 6000t/m and 10/12knots at 4500-5000t/mn in speed cruising. I can't change outboard now because it was new when I buy this boat last month, but I shall buy trims tabs. Regards

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Message 18 of 22
Posted by member Angus Geddes on Saturday 23 July 2005

Hi Defay, I had the same boat same engine. I could get about 10 or 12 knots at full throttle. Also have trim tabs. It is a good engine but not enough power for sea work. Have changed to a 70hp engine , this is much better.

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Message 17 of 22
Posted by member Defay Jean-Louis on Monday 4 July 2005

I had bought this week in Britain a Hardy pilot 20 with only Honda 50hp 4 stroke. What are the maximum performances possible? (sorry for my bad English). best regards

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Message 16 of 22
Posted by member Ian Martin on Monday 23 May 2005

Hi Damian If you give me a call on 07740087877 we can arrange to me up. Regards Ian

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Message 15 of 22
Posted by member Damian White on Saturday 21 May 2005

Hello Ian, Thanks for your comments on the Hardy 20 setup which I found very informative.I am interested in the 20 and am considering purchasing one in the not too distant future and was wondering as I live in Bangor if it would be possible to have a look at yours sometime as I have only seen others on the web. Best Regards, Damian

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Message 14 of 22
Posted by member Ian Martin on Sunday 15 May 2005

Hi Steve Now that I am in the water and have a chance to test the new confirguration I can report excellent results. The information supplied by your goodself and others proved invaluable. The sea conditions in Belfast lough tuesday past were ideal for carrying out full throttle test. I left Bangor Marina and proceeded towards Belfast Port, I gradually opened the throttle and at about ten konts started to deploy the trim tabs. I bought the new Lectrotab oval indicator when purchasing the Trim Tab kit, I have to say it's an excellent piece of kit, a tad expensive but worth it. The sea condition was like a millpond, no wind and slack tide. With the tabs fully deployed and throttle wide open revving to 5800, the pilot powered along at 20.7 knots. This was recorded on two GP's and paddle wheel fitted to the boat. I have to say the Pilot didn't feel right at that speed, bearing in mind the hull is not designed for that purpose. The engine prop configuration was spot on, no complaints there. The weigh configuration during the test was a follows, 2x25 litre tanks (full) port & starboard aff lockers, 2xgas cylinders port rear locker, 1xleisure battery starboard locker, 1 x heavy duty battery starboard side at helm, triangular water tank (full 125 ltrs)bow compartment, myself 12½ st and the usual pruck. I held the throttle open for a good 10 mins and then trottled back, retracted the tabs by 2 clicks and settled down to about 14.5 knots, the boat handled superbly. At Holywood YC I headed across the lough towards Whitehouse than on to Carrickfergus, Cloughan Jetty and back to Bangor, total fuel consumption about 14 ltrs of fuel. Thanks again to Steve P, Steve S and Hardy Marine. We are planning a trip over to Portpatrick soon so we'll see how that goes. Ian

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Message 13 of 22
Posted by member Stephen Pickthall on Friday 13 May 2005

Well, further to the great debate and just out of interest, has anybody got any further comments on the Suzuki 70's , and the trim tabs now that they have them fitted ? Please let us know.

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Message 12 of 22
Posted by member Ian Martin on Wednesday 16 February 2005

Hi Steve P Many thanks for the reply. Going on the information received from yourself and Steve S I think I will go with the 13 inch prop. I receeived an email from Hardy they also fit the 13 inch prop on the 70/4 to the Bosuns. I don't fancy the idea of having to change props, 2 owners and Hardy themselves recommend the 13 inch prop so on it goes. If I need any further info I will give you a ring. Best wishes.

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Message 11 of 22
Posted by member Steve Pickthall on Monday 14 February 2005

Hi Ian. Firstly let me say that my Suzuki was originally supplied with a seventeen inch pitch prop. I am told that on average you lose 500 revs with each inch of pitch. With the 13 and three quarter by 13 inch pitch the engine will rev close to its permitted limit with a loaded boat, which means basically that the boat was correctly propped. I would guess that with the 15 inch prop yopu might lose 1000 revs, but each boat is different. Why not try the 15 inch prop first, allow your engine to get run in and then see if it will rev to around 5700 rpms. If it will go no where near, then it is over propped and you will need the 13 inch pitch. It is a little bit of try it and see, I am afraid. All I can tell you is that my Pilot se , now owned by steve streets , revved quite comfortably to its allowed upper limit of 5700 rpm, even with a good load on board which means that the boat was correctly propped. Ring me on 07768 668861 if you want to have a chat about this, or I am afraid this notice will turn into a ten page essay. Best wishes, and happy sailing

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Message 10 of 22
Posted by member Steve Streets on Friday 11 February 2005

Ian, My Hardy has trim tabs fitted which you also may wish to consider in view of carrying 4 adults. It helps the boat get on the plane so much easier. I have had 5 adults plus gear and still had 19kts. For more details on trim tabs, I think previous postings from Steve Pickthall are still live on the site which you may find of use. Regards

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Message 9 of 22
Posted by member Steve Pickthall on Friday 11 February 2005

Just another point that might be of interest. My Hardy Pilot now owned by Steve Streets did have lectotab trim tabs fitted. As for the 15inch prop, you will probably find that that is ok when the boat is lightly loaded,but I do think the thirteen and three quarter or the metric equivalent is still your best bet.

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Message 8 of 22
Posted by member Ian Martin on Friday 11 February 2005

Hi Steve P. When you had the 15 inch prop fitted how did the Pilot perform i.e revs, knots etc? Was there a big difference between the 15 inch and the prop actually fitted?

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Message 7 of 22
Posted by member Ian Martin on Thursday 10 February 2005

Hi Steve S, I am pleased at the results you have been getting from your configuration,lets hope I obtain the same performance. Many Thanks for your contribution.

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Message 6 of 22
Posted by member Steve Pickthall on Wednesday 9 February 2005

The best prop I found and I believe used by Hardys is the thirteen and three quarter by thirteen inch available from Suzuki for If I remember around £ 80. This will allow the engine to rev to 5700rpm , suggested top revs by suzuki, but under light load a little care is advised to watch that you do not over rev, although there is an inbuilt limiter on this engine , I believe. Hope this helps. Steve Pickthall

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Message 5 of 22
Posted by member Adam Easton on Wednesday 9 February 2005

Hi Ian, There is a web sit where you can down load software to calculate your ideal prop size. visit: www.castlemarine.co.uk/pitch.htm

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Message 4 of 22
Posted by member Steve Streets on Wednesday 9 February 2005

I bought Steve Pickthall's Hardy Pilot and can certainly confirm that the prop he recommends is perfect. I have had a maximum 23kts and can cruise all day at 17kts.Hope this helps, and once again Steve thanks for the perfect boat.

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Message 3 of 22
Posted by member Ian Martin on Wednesday 9 February 2005

Hi Guys Many thanks for your help, I'll go agead and fit the 3x349x330. The load I'll be carrying is the usual fuel/water tanks, gas, batteries, and 4 adults and other anxilary equipment. Adam I'll download that software you identified. Steve, as a matter of interest what sort of speed are you getting from your pilot? Richard maybe you would back and let me know how your vessel performs with 70/4.

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Message 2 of 22
Posted by member Richard Nicol on Tuesday 8 February 2005

Ian I enquired about this - Steve told me that 13 3/4 is the size he finds best- I also called Hardy, they have the same engine on their demo Bosun - they quoted the size as 3 X 349 X 330 which I am told is the same as Steve recommends - my engine dealer said they'd normally fit a 15 inch with that engine - but agreed its best to follow Hardy's advice. My new engine is being fitted at the moment - so I will soon find out!

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Message 1 of 22
Posted by member Ian Martin on Monday 7 February 2005

I will be fitting a new Suzuki 70hp 4stroke to my 1991 Pilot during March. I noticed in the engines section a while ago a member had a similar issue regarding prop size, pitch etc. Unfortunately it does not appear to be on the forum any more. Can anyone with a Suzuki 70/4 fitted to a Pilot help with prop size. Many Thanks

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