codpiece Posted March 26, 2008 Report Share Posted March 26, 2008 Hi there, I am new to the club but seek your opinions on the merrits of 4stroke v 2stroke in Yamaha 15 hp, I have an orkney longliner and am looking to re-engine. ''CODPIECE'' Quote Link to comment Share on other sites More sharing options...
TomBettle Posted March 26, 2008 Report Share Posted March 26, 2008 Hi Codpiece Welcome to the best small boat fishing club online and the best real one anywhere on the South Coast. Good little boat the Longliner, but with her displacement hull the only thing you'll get more of with all that Hp is fuel consumption. A 15Hp is a lot for that boat and 10Hp will be plenty to push you through anytide run at her normal displacement speed. So: 1) Use a slightly smaller engine to save money on the purchase and also on fuel. 2) A 2 stroke is likely to cost considerably less to purchase and service but 3) A 4 stroke will be very much sweeter to live with and cheaper on fuel If pure budget isn't the issue then I'd be looking to get a 4 stroke, if budget is more of a question then go with 2 stroke. Good luck Tom Quote Link to comment Share on other sites More sharing options...
codpiece Posted March 26, 2008 Author Report Share Posted March 26, 2008 Hi Tom thanks for the advice, I am going for a 15hp basicly because that is what Orkney advised as the ultimate engine size. Codpiece. Quote Link to comment Share on other sites More sharing options...
TomBettle Posted March 26, 2008 Report Share Posted March 26, 2008 Hi codpiece I think you'll find that is the maximum rated engine size rather than the ultimate engine size. The longliner is a very good "Displacement" hulled boat. It is designed to go through nasty weather slowly, but steadily. Another PBSBAC member (Afishionado) quotes a formula for the maximum speed for a displacement hulled boat. The formula is the square route of the hull length x 1.5. So the square route of 16 feet is 4 x 1.5 gives a maximum speed of 6 knots. That speed could easily be achieved in fair conditions with a 6Hp engine. Going to a 10Hp engine would simply mean that you will be able to keep punching through at 6 knots in far worse conditions. A 10Hp, in my opinion, is by far and away the best maximum size for your boat. Anymore Hp will simply dig the boats stern in a bit and push a big hump of water in front of you. You won't go any faster (unless the tide is with you), but yuo'll burn upwards of twice as much fuel. It's obviously your choice, but I promise that there is no need for an engine that size. It will work with the boat, but it will be a waste of money. Quote Link to comment Share on other sites More sharing options...
Adam F Posted March 26, 2008 Report Share Posted March 26, 2008 Tom, Is the Longliner a full displacement? I thought it was a semi-displacement?? Adam Quote Link to comment Share on other sites More sharing options...
Coddy Posted March 26, 2008 Report Share Posted March 26, 2008 Having used a Longliner in my previous club for a number of years I would agree with Tom that a max of 10hp would be fine. I know the Orkney advert shows a Honda 15hp but I think this is way overkill. I use to fish on the east coast at Felixstowe and launch from the beach! We needed a good engine to get away from the breaking waves quickly and we used 5hp Seagull engines which were fine and then got a 5hp 4-stroke which went even better. Save your money if buying new and get a cheaper lower horsepower engine. Just a thought, if running a 2-stroke at tickover for a length of time they can cut out/stall or not respond quickly when the throttle is opened, just one of those things with 2-strokes. If you intend to do trolling around the coast go for a 4-stroke if you can. Regards Coddy Oh forgot to add welcome to the best forum Quote Link to comment Share on other sites More sharing options...
TomBettle Posted March 27, 2008 Report Share Posted March 27, 2008 Tom, Is the Longliner a full displacement? I thought it was a semi-displacement?? Adam Displacement hull Adam. You are thinking of the Fastliner Quote Link to comment Share on other sites More sharing options...
duncan Posted March 28, 2008 Report Share Posted March 28, 2008 personally I would get the Tohastu 9.8 2 stroke for that boat - it's the lightest in class with loads of torque. Easy to remove for storage and safety if you choose (sub 30kg?) I haven't experienced oiling up with 2 stroke OBs for a long long time. equally the noise is as much model dependant as 2 v 4 stroke at these sizes On the other hand it may not be available anymore as a new unit Quote Link to comment Share on other sites More sharing options...
gaffa Posted March 28, 2008 Report Share Posted March 28, 2008 personally I would get the Tohastu 9.8 2 stroke for that boat - it's the lightest in class with loads of torque. Easy to remove for storage and safety if you choose (sub 30kg?) I haven't experienced oiling up with 2 stroke OBs for a long long time. equally the noise is as much model dependant as 2 v 4 stroke at these sizes On the other hand it may not be available anymore as a new unit Seems to be still available from Holes Bay Marine see price list on link http://www.holesbaymarine.co.uk/tohatsu/Tohatsu2stroke.htm Reviews keep stating that the 2 Stoke Tohatsu Engines are Bomb Proof however no experience with them personaly Peteg Quote Link to comment Share on other sites More sharing options...
codpiece Posted March 28, 2008 Author Report Share Posted March 28, 2008 THANKS FOR ALL THE GREAT INFO AND ADVICE. (MY HEAD HURTS!!!) GREAT, FRIENDLY CLUB, GLAD I JOINED. CODPIECE. (DEREK) Quote Link to comment Share on other sites More sharing options...
Coddy Posted March 29, 2008 Report Share Posted March 29, 2008 Seems to be still available from Holes Bay Marine see price list on link http://www.holesbaymarine.co.uk/tohatsu/Tohatsu2stroke.htm Reviews keep stating that the 2 Stoke Tohatsu Engines are Bomb Proof however no experience with them personaly Peteg They use this make of engine for Zapcat racing, it's the only manufacture that guarantees the engine for racing! In fact it is the only engine allowed for racing Zapcats! Coddy Quote Link to comment Share on other sites More sharing options...
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