Yacht Motoring Speeds ??

[RHP]

Fifty years ago, 'boat' engines were small and slow. Today thats not the case, yacht engines are small, reliable, light and very capable.

Many of us have to leave a marina, port, move from tidal moorings to the open sea before we can sail etc.. so why have yacht designers left us with the same 5-6 knot speed that we have 30-40-50 years ago? Hull design has changed, keel configurations, boat weight and materials and manouvreability so why hasnt yacht design evolved to the point where a yacht can safely motor (as an option) at 10-12 knots?

The MacGregor 26 of course flies along under a 50hp outboard, so it is possible however a) its butt ugly and b) I´m looking for confirmation its possible for the majority of boats. Surely all lift keel yachts should be able to do 12 knots safely under power say with 20% keel down for directional stability. Shoal draft as well?

We have a 3-4 hour tide window and we lose too much time phutting around at 5 knots.... we need 10-12.

[Fanie]

You don't want to make waves to upset other boaters
You don't want to create the impression you stole something and is making a getaway
You don't want someone to pull out right in front of you when you're hitting 12kn

What were you hoping to do when you get out earlier

[RHP]

Thank you Fanie, I appreciate your vision.

Motorcruisers pass through the same waters at 10-15 knots so why not a yacht?
Are you infering all motorboaters are thieves making a getaway?

You´ll have to come up with something better than that laddie......

[Fanie]

Hi RHP,

Vision ? What vision. I wish I did get them.

If there's no reason why you can't go that fast, why don't you ? If it's reasonable and safe to do so let rip. If it's not against the law then I don't see a problem.

Maybe it's those stiff upper lip snobs that just go so slow to show how important they are and wants to be seen.

Maybe they're really old and go slow because they get scared if the scenery changes too fast.

Maybe they're looking for a parking spot.

Maybe someone's hat blew off last time they were there and is looking for it. Hey, you never know !

Or even like you said in the first post. They have very old and slow motors and that's what they can get...

[tom28571]

RHP,

I have the feeling you already know the answer to your question. "Cruising" sailboats are designed to sail and meet the needs of the public. Even the usual racing sailboats will not usually get the speeds you want. To go 10 to 12kts, monohull sailboat has to sacrifice interior amenities as well as have a hull that works well at those speeds and will probably be a poor sailer. It can be done if you are willing to spend the money or just buy the 26X.

The option is a multihull that can make 10 to 12 kts and still have some creature comforts.

[Fanie]

Hi Tom, he knows the answer as you say. To now he's been too scared to go any faster. I think he's just getting bold and pushing his luck.

THP, when do we get to see the NZ pics eh ???

[Easy Rider]

No Hull designs have changed very little and the relationship between wave length and boat length hasn't changed at all. Sounds like your'e one of those people that think technology will always make your dreams come true. Modern sail boats have optimized their WLL and are lighter but sail boat speeds are still almost totally limited by their own wave length. If you really want to go 12 knots (like I do) get a power boat and go any speed you can afford. I have the power boat but for economy and range I go 6.15 knots. And if your'e usuing the term "yacht" exclusively for sail boats my dictionary does not differentiate.

Easy Rider

[TollyWally]

Good to see you back EZ,

LOL, my dictionary defines a yacht as a boat that doesn't work for a living. I actually find the term mildly pretentious in an amusing sort of way.

[Easy Rider]

Thanks Tolly,
And I think you did better than your dictionary and mine ... Pretentious.
Perfect.
Easy

[Dr. Peter]

Going back to Tom's point about multihulls. It was almost a throwaway line but I think its an idea with merit.

Most trailersailers have a small outboard (5-10 hp) for manouvering out of the dock and motoring in the calms. In my experience these motors rarely push the boat any faster than it can sail. The Macgregor 26X or 26M is an entirely different proposition. The upside of course is that fuel use is really low.

I recently started sailing an OTB catamaran after sailing dinghies and trailersailers. And if there is a decent wind to power up the sail it goes like the proverbial rocket.

That suggests to me that the right amount of power would push a catamaran really quickly in the calms.

Does anyone have any experience of pushing a trailerable size cat with an outboard? How did it go?

Peter

[RHP]

Originally Posted by Easy Rider

No Hull designs have changed very little and the relationship between wave length and boat length hasn't changed at all. Sounds like your'e one of those people that think technology will always make your dreams come true. Modern sail boats have optimized their WLL and are lighter but sail boat speeds are still almost totally limited by their own wave length. If you really want to go 12 knots (like I do) get a power boat and go any speed you can afford. I have the power boat but for economy and range I go 6.15 knots. And if your'e usuing the term "yacht" exclusively for sail boats my dictionary does not differentiate.

Easy Rider

Thanks the answers guys, except for Fanie who I hate.

Yacht design may have evolved to maximise WLL (as much accomodation driven as for sailing characteristics), I agree wave lengths have not changed (isnt Neptune upgrading over time?) however if any shape of motorboat from slim pencil forms through to oversquare trawler yachts can push themselves to 12 knots with various levels of efficiency, then why cant a yacht?

Yacht engines are auxiliary power, in principle a yacht should use its sails 90% of the time so you could accept the hull running at less than full efficiency to get to your intermediate destination (ie into the open sea from your mooring). I guess the smaller the yacht, the greater the relevance as day sailing is more prominent.

You know I´m right, yacht design has taken its eye off the ball....

[CT 249]

Well, RHP, there's two options. Either you are vastly smarter and more innovative than almost every other member of the world's sailing community, or your concept is an old one that has failed to achieve its goals.

As you agree, there are ARE boats out there like the Lancer Powersailor and Mac, and they just show the issues. You can't just throw an engine big enough to get your average yacht up to that sort of speed (plus the fuel tank, plus the reinforcement, plus the high-drag prop, shaft and bracket) without losing the 10-12 knot sailing speed the boat supposedly has.

I'm no expert, but a quick look at comparable boats and motors seems to show you'd be looking at an extra 200kg or so of engine and hull, plus a high-drag multi-blade prop, to drive a 30 footer well above hull speed, so suddenly your lightweight 30 that can sail to 12 knots is no longer a low-drag boat.

The little I can find about the Lancers indicate that the 27 Powersailer was about 10% slower than the sailing hull is was rumoured to come from, and that's despite the fact that the 27 had the light, low-drag option of an outboard rather than a diesel. Sure, there were other differences between the two designs, but ten percent, roughly speaking, is about the difference between the typical 30 footer and a 40 footer of identical style...that's a vast amount of sailing efficiency to lose.

So it doesn't seem as if the rest of the sailing world is stupid; they just don't want to make their boats slower.

[RHP]

Hi CT, many thanks your interesting response. I´m vastly smarter than no one, especially on this forum.

Its difficult to counter your comments as obviously weight is a vital issue, especially on smaller yachts. I need to think.

I shall return.

[RHP]

I have returned, a photo of the French built Kerkena 13.5 The website states shes motors at 15 knots!! Not bad for a 45 footer.......


http://www.go-catamaran.com/monocoqu...cht.php?ref=14

Some other nice small yachts on that website.

[rwatson]

Originally Posted by RHP

Fifty years ago, 'boat' engines were small and slow. Today thats not the case, yacht engines are small, reliable, light and very capable.

The MacGregor 26 of course flies along under a 50hp outboard, so it is possible however a) its butt ugly .

Yeah, its true. I wanted the speed and the sailing power, and also an inside Nav station - so I got the concept re-designed.

Not nearly as ugly, and faster because it is 2 ft longer, and more advanced hull design.

Able to be built by amateur people like me - just arranging for a shed ...