British Seagull vs. Fisherman

[Squeakit]

After replying to Jonboatman's post, I have a question. My 5hp Seagull is supposedly designed for displacement hulls (like sailboats) which never plane out - it is geared low and has a big prop and gearbox. My old Fisherman 5.5hp has a small streamlined gearbox and 2 blade prop and is designed more for planing hulls. In trying to get more speed from the seagull, my question is this. Is a 12 foot displacement hull top speed faster or slower than a 12 foot planing hull running at its top DISPLACEMENT speed? In other words, if I put this motor on a 12 foot sailboat hull would it be faster or slower than my 12 foot planing hull, other factors being equal?

 

[steelespike]

Re: British Seagull vs. Fisherman

A displacement hull has a maximum design speed<br />It will vary depending on length width weight and<br /> And hull form. Displacement speeds should be<br />considered single digit speeds though some are <br />much faster. A planing hull would tend to be slower if unable to plane but again design plays<br /> a big part in determining speed.<br /> There is a Sea Gull site that races sea gulls<br /> And while I only skimmed the site it appears they are using displacement hulls.

 

[Squeakit]

Re: British Seagull vs. Fisherman

Thanks for the reply, Spike. I'll see if I can find that racing site. The other factor that makes the Seagull slower is probably the gear ratio - kinda like driving a car in low gear. Lotsa grunt, no speed?

 

[steelespike]

Re: British Seagull vs. Fisherman

Squeakit, found a site "Saving Old Seagulls" at:<br /> www.saving-old-seagulls.co.uk Mentions racing.<br /> When searching I think it works better if you<br />include British in you search wording.

 

[Squeakit]

Re: British Seagull vs. Fisherman

Thanks for the link, Spike. GREAT website! Any other British Seagull owners out there? Fascinating and simple motors. Mine's a 1979, but it looks like something from the '20's or '30's and never fails to elicit comments and questions. Not fast, but fun.

 

[Tinkerer]

Re: British Seagull vs. Fisherman

Squeakit<br /><br />Lke you said about grunt, in car terms British Seagulls sacrifice speed for torque, so a small motor can push a big boat, like a 23-25 foot yacht, but at a relatively slow speed. <br /><br />I put my rated (ratings on early models are suspect) 4hp British Seagull (2 blade 9 inch prop) on my 12 foot timber dinghy and got it up on about half plane at about half to 2/3 throttle, but going to WOT didn't do anything more, except increase vibration, noise and, the trademark of the early Seagull 10:1 fuel ratio, smoke. You are guaranteed to get attention from other people that people with quiet, smokeless modern motors don't get.

 

[Squeakit]

Re: British Seagull vs. Fisherman

Hi Tinkerer: Fortunately my Seagull is a '79 model which uses the 25:1 ratio and doesn't smoke. Actually I run about 32:l and doesn't seem to bother it. After a day's running around however it sure does leak alot of unburned oil from the bottom of the exhaust leg. Agree with the suspect hp rating as well as the performance. My next project is to borrow someone's GPS and compare throttle settings with speed. 2/3 throttle seems to be as fast as the boat will go and the rest is noise. One good thing is the hard plastic impeller never wears out unlike modern rubber ones. Why don't modern OB's use this type of water pump? Must be a good reason.

 

[Tinkerer]

Re: British Seagull vs. Fisherman

Squeakit<br /><br />Seagull changed their HP ratings maybe 1960's and old ratings went down. I think original rating system might have been some odd system only Seagull used. <br /><br />Mine's a 1954 Model 102 with cast one piece head. Have run it on 25:1 with conversion kit but doesn't make any difference, except less smoke. <br /><br />Beauty of the British Seagull is its simplicity, in water pump and everything else. Compared even with my 1976 5hp Mariner and 1967 60hp Evinrude, which aren't exactly modern high tech, it is stunningly simple: flywheel magneto, points, basic carb, and can be rebuilt on the floor of the boat in a heaving sea (not that I'm ever likely to be out in one)with a screwdriver and shifting spanner. No battery or retracting pull start, so can be started with a bit of good string. Fires on about one complete rotation of flywheel. I've even managed to start it by spinning flywheel with my hands. <br /><br />Tough, too. I ran mine (unintentionally) already full hot at WOT driving 12 foot dinghy for about 5 minutes with no water pump operating and it still started fine once it had cooled down.<br /><br />I'm no engineer, but the simplicity of design is impressive. <br /><br />I guess they don't make water pumps like that for the same reason they don't make a lot of things like they used to: weight, cost, and planned obsolescence.

 

[Link]

Re: British Seagull vs. Fisherman

Great website steelespike <br />And thanks, I've been looking for information on them Good little engines <br />If you like simple and I am <br />I also like odd things and they fit the bill! But then so do I! I still think steelhead are real fish! haha <br />Happy Boating Link