The correct engine!

[jonno]

Thanks too, Jonathan and Rob, for trailer advice.

John

[Michael Rogers]

Jonathan, with reference to the "Search" advice in your post of 19 August, could this be repeated somewhere at the top of the Forum index page, so that it's accessible and we don't have to remember that it's buried in "The Correct Engine"? I think (Hope) this would be generally appreciated.

Michael

[Jonathan Stuart]

Done! I have created a "sticky" topic about searching in the General area (sticky means it will stay at the top of the forum and newer topics can't move ahead of it).

[Peter Taylor]

I use a Tohatsu 5 on my BR - it may be useful to look for a specified sail drive prop, but I'm not sure if they come on o/b's that small.

The sail drive prop only comes as standard with a long shaft motor - no good for an SB outboard well. However I bought my short shaft 6hp Tohatsu with the sail drive prop fitted as an extra (which cost mega-extra... but at least I now have a spare propeller). How much difference the different prop makes I've no idea but the motor certainly pushes my BC20 along very well.

The mistake I made was buying the version with an internal fuel tank. I never use it and the filler cap and it's air vent closure simply serve to foul the control line of my Tiller Tamer plus any other ropes that come that way. Another time I'd just have the external tank version.

Peter

[Rob Johnstone]

Vagabond sports a 6hp Mercury (Freddie). When first installed Freddie had a standard power boat prop which was changed to a sail drive after the first year. It's made the speed of Vagabond more controllable at low revs and seems to have improved the "miles per litre" on the cruise by about 10 - 15% with (as far as I can tell) no impact on top speed in calm conditions (about 5.5 knots through the water). I can't say that I've noticed any difference in noise level - "loud" in all cases!

Rob J

By the way, the Swallow Boats stand at the Southampton Boat show today was an owners convention! I think we had more owners that potential customers.

[david]

Hi All, old thread but still pertinent, at least to me! I have a 2hp Honda and love it. Always starts on first or second pull. Trouble is that it does not have neutral or reverse. I posted that I had not had any issue with the no reverse. Turning the engine was always OK! I guess I should have waited until I had to maneuver in a tight marina in windy conditions before I spoke. (Lets just say it was more fun for the spectators than for me and I am sure there is a you tube video of it somewhere!).
 I am now the proud owner of a 6hp Tohatsu - That has neutral and reverse! It maneuvers much easier. The real reason for the purchase was that I was caught out a couple of weeks ago,  about 2 miles off shore on the Pacific with a "Santa Ana" wind condition, on the nose, about 25-30 miles per hour. If not being able to furl the jib completely and have it flog the whole way in was not bad enough, it seemed that there were times I was actually going backwards, being blown out to sea, with my little 2hp working just as hard as it could to get me home! Yes I made it back after a tense motor back in. The old motor was working as hard as it could - Got to love it - But was really on the limit! I had to fill the internal tank up on the way in also.. Did I mention that the waves were also fun with this wind? OK, so in case I ever get into that situation again, I now have the motor to get me out of a tense situation. I am glad I did not have to go to "plan B" and divert to a different harbor as that would have been just too much!

[Graham W]

I really don't agree with the "one size fits all" philosophy that used to be broadcast in the early days of this forum.  If you are racing and only need your engine or motor for occasional use, it should be something small and lightweight.  If you are also cruising and regularly dealing with long distances and strong winds and currents, you need something altogether bigger and punchier, otherwise you risk getting caught out.  If you both race and cruise, then you probably need one of each.  If you can only afford one, then safety says that it should be the big one.

[david]

Hi Graham, I second, by my experience above,  your opinion that - "If you can only afford one engine, then safety says that it should be the big one".
 

[Tony]

Is there much of a difference between the needs of a Br 20 and the Br20exp when it comes to engines? It could be - but I don't see why.
My experiences with "Four Sisters" a Cardigan Bay Lugger (Storm 19 with a lid) and "Wabi" my Deben Lugger Hybrid (a prototype lug and mizzen with a heavy layup and big mainsail) lead me to wonder.
I have a 3hp Mariner twostroke and 4hp Yamaha fourstroke. Huge difference in weight and convenience but not much in performance, you might think. However, against head winds with short steep seas "Four Sisters", elegant creature that she is, rises to each wave, doesn't ship a drop of spray but really needs the extra grunt of the  4 horse if she is to make any progress. "Wabi", on the other hand, smashes through the mucky stuff without a care in the world, joyfully soaking everyone  in sight with spray in the process but easily reaching hull speed (7 knots or so) at two thirds throttle with just the little 2 stroke. Very odd.
Perhaps, at the next Swallow Boat Fest, BayRaider and BREx owners could do a few engine swaps to see if there is any significant  difference between these two very similar hulls?
....Or, Just for a laugh, arrange a series of Tug-of-War contests between differently engined boats. (My money's on the 6hp Yamahas!)

[Graham W]

Further to Tony's post, I've heard it suggested that filling the ballast tank helps the engine on a BR20/BRe to propel the boat through a short chop.  Something to do with momentum being provided by the extra weight, a different underwater profile and maybe a tiny amount less windage.  So without ballast, the boat is more like 'Four Sisters' and with ballast more like 'Wabi'.  Has anyone tried experimenting with this?

[Tony]

Hi, Graham.
Definitely, the more mass the greater the momentum.
Sailing "Four Sisters" without her 90kg of lead ballast is fine - on flat water and sensible winds - but at sea, the ballast really does help her go to windward against a chop. The same when motoring. A good slap from a wave stops her dead without the ballast. You have to wriggle through the waves to make progress.
Variable ballast on the BayRaiders/Cruisers is a great advantage, which ever engine you decide on.

[Peter Taylor]

Motoring through a chop (or waves in general), I think more mass and hence more momentum is always an advantage.  Apart from the factors mentioned, if you are bucking over the waves rather than cutting through them there's the chance the propeller comes near enough to the surface to entrain air and loose thrust.  Admittedly that is more of a problem with a transom hung outboard (where the propeller might even break the surface) but air entrainment is still  a possibility since we use short shaft outboards because of the outboard well geometry.

Using the Torqeedo I used to empty the ballast tanks when going against the current in the river (where the waves are very small or absent).  Whether having less boat in the water made a significant difference, I've no idea.    With the 6hp Tohatsu I've got power to spare so don't bother.

Peter

[Andy Dingle]

Getting a bit off topic now but ...

Wot I don't unnerstand is.. surely the surface level of the water in the ballast tanks lay at the same level as the surrounding water? And therefore has no weight?
The ballast therefore only comes into play when the boat is heeled and the ballast (water) is lifted clear of the surrounding water, it's weight then comes into play and it tries to maintain equilibrium and keep the boat upright.
A container of water submersed in a tub will only weigh the weight of the container - only when you lift it out will you feel the weight of the water plus the container?
Get rid of the water (ballast) and we are left with just the weight of the container (boat) which, of course, is what makes our boats such perfect trailer sailers.

My thinking is therefore - and my own experience seems to support this - that the boat sails (or motors, or rows) as well, if not better, with the ballast tanks full. Of course there is the effort required to get the weight of the water ballast moving in the first place - but if there is no weight, then the effort to move it must be minimal? Unlike conventionally ballasted boats, where the ballast is heavier (denser?) than the surrounding water and takes a lot more effort to get it moving?

Now I am confusing even myself! There must be better minds out there than me who can explain the physics behind water ballast?

I recall sailing with Jonathan on Caledonia last year in my old BR20 with empty tanks, the (notorious) short steep chop on Loch Ness was hitting us on the bow just as we were tacking, the weight of the waves kept knocking us back into stays - I am convinced this would not have happened if we had the weight (but not weight!?) of water ballast to give momentum to carry us through the tack. Indeed, in the recent discussion about raising the main underway, single handed, I always would maintain having the tanks full to give the boat momentum to carry the bow through waves intent on knocking it off your hoped for course.

Maybe worth a library article if someone can explain in words of one syllable the physics behind water ballast!

Andy
Baycruiser23 No.25 'Equinox'

[EDWIN DAVIES]

I think momentum and inertia are what are what affect your sailing.

[David Hudson]

Surely once water is taken on as ballast, the adage that water finds its own level does not apply. That is why cargo ships take on ballast to aid stability and the ship settles lower in the water.

If is Friday 13, not a good day to stick my head above the Parapet?