why aren't there fast planing sailing dingies able to take outboard motors?

here is a better older thread including some powered planing sailboats.
planing sail boat hulls https://www.boatdesign.net/threads/planing-sail-boat-hulls.60286/

 

Not much payload, mostly thinking of new style of small fast boats that have hulls designed for planing VS prior generation (Laser, etc) that seemed more semi-displacement. RS Aero - Wikipedia https://en.wikipedia.org/wiki/RS_Aero It seems like it could make a decent dual use outboard powered (moderate) speed boat, but IIRC they really don't have any baked in provision for an outboard, and you'd really need to butcher it to add one.

Seems like a small amount of extra weight, material and money could have made a boat like RS Aero into a dual use. Leverage whatever added strength is at the outboard motor bracket to bolster the rest of the boat, maybe a durable self rescue handle or tow cleat. Yeah, one day at the lake I saw one little sailboat towing another that had gotten demasted/desailed.

 

Laser Stratos would plane under sail, and could be fitted with an outboard. They stopped production.

 

Are you still thinking about the same concept since 2011?

how about a 25hp outboard on a planing sailing dingy? | Boat Design Net

 

Dinghies with 150 to 200 sq ft of sail are planing with about 4-6 HP in a strong breeze. Why add 20HP to increase speed marginally? If you are scared of heeling and getting wet, what makes hot sailboats fun, get a stink boat.

 

Squidly-Diddly, it would appear you are unable to pull the trigger on your project.
If you can't find a design that suits you, then you may not have reasonable expectations.
What's your take on the situation?

 

I'm waiting for a cheap, or free, beater RS Aero or similar Wonder Boat to show up on SF Craigslist, then I'll pounce on it and figure out how much butchery it will take to slap a small outboard on it. Might even add oarlocks for either fixed or sliding seat rig, which shouldn't need to be extended too far as these boats are already nearly 5' beam, and maybe the extensions could even double and outrigger seats or make the seating area a bit more comfy. AFAIK such extensions wouldn't interfere with sailing (or motoring). Sure it wouldn't row to well with sliding seat weight transfer, but unlike a shell it would be nice and stable and not require active balancing.
SOR includes being able to car top on a full size wagon.

Next stage would be adding a small outboard to one of those hydrofoil sailing dinghies. If the problem with planing a small beamy boat is chop, adding a motor to a small hydrofoil could be interesting.

 

Ah, I see. Thank you.

And how long are you willing to wait?

 

It might be possible to move the outboard inword by setting up a well. This would get the weight out of the end of the boat. But I think this well would require a tunnel aft it which would have a top that was higher than or at the waterline. This is so the stern would not scoop up water as the boat goes forward. It may be more reasonable to expect it to sail at displacement speeds but power at planing speeds (except possibly on downwind courses of say 135 degrees or more off the wind). Such a boat would not require a huge sail area or hiking straps, but would be able to make port quite quickly, should the need arise, as long as the distance isn't too great.

This I think would vastly improve the utility of a sailboat, especially if we move into an era of electric power, which delivers very limited range at higher S/L speeds.* This would fit in well with the tradition of smaller working sailboats that were around before engines became available. Most that, were around 20 ft or less, were designed to be rowed. These had rather limited beam, typically 0.30 Length or less.

Now, with lighter more powerful engines (or even electric motors), it may be possible to go with greater beam, which usually brings about more useful space onboard.

Lower aspect ratio sail rigs, with spars short enough to fit within the hull, might find higher popularity, if such boats were to find wide acceptance.

For both higher powering speeds and higher sailing speeds, it may make more sense to go with multihulls. The types I think would be most suitable would be pahi-style catamarans, with the accomodations within the hulls, instead of on the wing deck, and double-outrigger style trimarans, with less than full buoyancy floats. In both cases, I think it would be best to attach the engine or motor to the wing deck, which would be much shorter than the main hull(s). This would move its weight to a more central location.

* today's high performance batteries typically deliver about one hp hour (0.740 kw hour) per 3 lbs (1.36 kg) of battery weight. One half-gallon of gasoline typically delivers about 3hp hour (2.20 kw hour) of useful enrgy (to the propeller).

 

The fundamental point is the design requirements of a dinghy and a motor boat are different.
A motor boat can plane 100% of the time.
A typical dinghy only planes in certain wind directions and strengths.
I used to race a Laser and planing was a rare treat.
An ideal displacement hull and an ideal planing hull are very different.

 

I'm thinking the newest crop of wonder boat small 1 to 2 crew planing sailing dingies look much more geared for planing (all out racing), so that might make them better than prior gen (Laser) for planing with motor. However, these new wonder boats have open transoms or otherwise no clear path to mounting an outboard without major butchery, and I doubt those already flyweight boat's structures would take kindly to amateur butchery. But with a bit of forethought it should be able to include at least the basis for adding an outboard mounting plate, without any compromise in pure sailing ability, thus making the new wonder boats much more useful.