Sharpie Schooner 42 with an outboard motor

Hi Valery,

What's the displacement ? Our last boat was 36' on deck, ~20,000 lbs and it was fine for 2 adults, 1 dog, 1 cat (the captain). We decided to build bigger so we could have more room (storage). We might have gone a bit too big....

Put those masts on a tabernacle that you can raise and lower easily, and you have a super interesting boat for the first part of your plans ( Cruising and sailing from Montreal, Canada, St-Laurence River, the canals, Lake Champlain, The great Lake area, maybe eventually the great Loop), In my mind for a couple, maybe friends for a weekend or week.... but a family ??

Not every boat boat is good for everything, so if you really want to venture a bit more offshore with that sized crew it looks tight.

Cheers,
Mark

 

I'm fine with you grinding off the anti-ventilation plate, please show one where it's done with the larger diameter prop mounted on the shaft, that I'll count for reality.

This would be easy to show for you, since you say installers do so on most smaller mid range, and the smaller Tohatsu outboards.

 

I did say that I agreed with gonzo. A 10-15 hsp will propel the lightweight sharpie just fine (almost all of the time). I only said that if OP eventually chose the 25hsp high trust Yamaha, to get the 12 x 7 prop (AVAILABLE for it) as an option and don't run the engine max RPM-the only place where it might possibly cavitate. Somewhere between idle and 2/3 throttle (2/5 seems reasonable (5 knots - 880 prop rpm)-to me) he will find a "sweet spot" to his liking with absolutely no potential damage to the engine as it is well below optimal design line up to a fuzzy area somewhere between 7 and 8 knots (no accurate hull resistance data). If its not clear to anyone here that a 10 ton monohull (sharpie or not) is not going to jump up on plane (and introduce significantly different thrust/resistance figures) even if it reaches 9 knots (under power alone-up to 60hsp suzuki) down a big swell, then speak up. Otherwise there is no fault in my suggestion to agree also with OP and go with the 25hsp instead of the 10-15 hsp or the larger 50hsp. All of these outboards are going to experience serious resistance on the way to 8 knots and more serious resistance trying to semiplane above that, possibly in the case of the Suzuki 60. The 25 hsp Yamaha has militons of reserve thrust from idle till at least 7 knots. It would be nice to get the 12 x 7 prop off the Yamaha and put it on a 15 hsp Tohatsu, if it doesn't fit glue it and pin it on. If there is a next time take the shaft and prop to a machine shop. If it fails at sea you can tie it on. File some weight off the prop and use 6 knots as self imposed speed limit, realize the savings in fuel.
I know I switched manufacturers when I put the smaller diameter 13.5 x17 (from a chrysler 60 or 90 i don't remember but it was chrysler) prop onto a johnson 55. Maybe that example is no good because the 15" johnson prop probably would have fit the chrysler without modifying the anti-ventilation plate. You can look that up if you want, see if I would have had to do some "customization", then there is your example because it certainly would have fit the shaft. I would not worry about breaking an outboard shaft or gears, bearings yes, especially above 2/3 throttle.
I did not say that installers do so on most midrange and smaller Tohatsu outboards. They could if they choose to. I would. You edited first.

 

-or by people who don't have a specific name for it, and just view it as a major obstacle (and learned the name for it earlier today). All the boats I've owned with outboards put up with the extra drag because the prop finds its way out of the water completely at times even if I install it with the ventilation plate 6" below the waterline. Except one 20 hsp Johnson 25" shaft mounted in a sliding + tilting set up in the cockpit of a 36 foot catamaran built in 1963. Its prop ventilated constantly in any attempt to move the throttle past 1/2 despite the anti-ventilator plate. It weighed about 5000lbs with wet "deadwood" and saturated open cell foam. Still went 6-7 knots at 1/2 throttle. I don't think the engine had ever been replaced. That cat took seas well at speed! But with large rocker would hobbyhorse too much for the prop if you went too fast in 1-2 ft (waves). The engine was 1/3 the way forward of the stern too. I imagine the sharpie 42 in the same situation or worse.



wish I had owned the onedescribed below instead:

In addition to the Trans-Pacific record (held - old print) AIKANE X-5 also holds numerous other West Coast and Hawaiian Islands sailing records.

• Designation: Performance racing catamaran
• Length, overall: 62 feet
• Length, waterline: 57 feet 4 inches
• Beam overall: 31 feet
• Displacement: 14,000 pounds
• Draft: 17 inches
• Mast Height: 80 feet
• Sail area, working: 2,000 sq. feet
• Engines: Yamaha 9.9 hp, 4-stroke long-shaft outboard (x2) //// key words here- displacement 14000lbs and 9.9 hsp. also relevant the sharpie 42 also has less wetted surface area.

 

Goof balls at Choydesign do not even know their own boats. That is not my ex-boat IMUA! in the picture. There was no wheel on IMUA!. Also the bow is not right, IMUA!'s was raised a bit the last foot or so. Didn't have two boom vangs either, only one. That boat in the picture is probably IMI-LOA.

 

Yes a loud screaming engine due to resistance-free over revving when the prop is lifted out of the water is a problem, that's far to often seen on stern mounted outboards on sailboats, when the bow goes down off a wave and the stern is tilted up, which of course also gives loss of propulsion when it's needed.

Hence this is one of the reasons PAR advised Valery to mount the outboard within the waterline or close to it, see post #77 for this.

Goodwill To All mentioned in post #63 James Baldwin at Atom Voyages installing the outboard inside the lazarette in a well, which is also the area PAR suggests in post #77.

Here's an example: Atom Voyages → Triton #503 Refit → Part 1 → Part 2 → Demo → See the text and also the other jobs of this project at the linked pages.

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Demo: ​

The slot just aft of the waterline means there's no drag from the slot, and there's no buoyancy loss from a well within the waterline. And the leg tilting aftwards out of the stern means there's less tilting space needed inside the boat. The outboard's mounting space is closable to the inside of the boat when the outboard is down. The rest of the lazarette on both sides of the outboard can be used for gasoline storage.

 

Chinaseapirate, assume your OB location at cockpit for your referenced catamaran would be between the 2 hulls which would operate completely different than putting prop down under hull when running.

Btw, my thoughts now for catamaran underbody is flat bottom, no rocker, adding waterline length to extend aft to pointy ends rather than wide upsweep for clean exit. Catamarans need all the L to B increase they can get, keeping hulls narrow and immersed fwd would minimize pounding if it occurs way better than the hobby horsing rockered hull you describe.

Would hope pics shown from atom voyages have a WT bulkhead fwd of OB with sides sloped towards slot.

For a lifting OB the leg should have a permanent plate right at hull botom that fits perfectly to hole eliminating air suction then a spring loaded plug again, fitting perfectly to hole when raised doing away with drag.

The well hole would always have water upto WL but that would be minimal weight and loss of bouyancy

 

While we are doing photos, here is one of my old Cal 28 posted in a different thread. It shows how deep you can get the prop. This is what actually works here. The motor is a 20" Merc with a 5" extension making it 25". This boat ran off shore a lot in the '80's when it was a drug boat. I cleaned up her reputation a bit. The motor behind the rudder is a terrible idea if you ever want to back up, but this boat did keep its prop in the water in a seaway. Personally, I consider this to be about the upper size limit where an out-the-transom design can work for an off-shore boat. Bigger than this, and it should either be restricted to inland waters, or you need to move the well farther forward under the hull proper.

link to photo - Blackrock 24 https://www.boatdesign.net/threads/blackrock-24.46525/page-3#post-660160

 

Well, on the slim premise that OP can glimmer any useful info as to his SOR by speaking about catamaran hull shape...C/S/K catamarans never pound. ever. Ocassionally they "slammed" the bridge deck if traveling too fast in too big of waves, and an odd one forming from head on. Imua at her waterlogged weight may have been the worst of them all in that respect.We raced it once to Ensanada..DNF no wind. It was two time winner early her career, and capsized once (she had 50 foot stick and a 14 foot beam!). The mast was chopped to 44 by the time my father purchased it. Motoring head on into even 2-3 ft waves would produce "slamming"of the bridgdeck if going over 6 konts or so. I got chased around the boat once to avoid a thrashing only because i inched the throttle up gradually to get to fishing grounds sooner. One slam and a madman comes bursting out the cabin...

I know modern racing cats and tris have very little rocker. I'm aware that Lakota, Commodore Explore, and now an ORMA 60 trimaran have broken Aikane x-5 record Transpac crossing. The Orma 60 comparable to Aikane X-5 in length and weight had 70% more upwind sail area and god knows maybe 200% more downwind SA. It had a 60 ft beam compared to 31 ft. Different races conditions also 1989 race had less wind. Commodore Explorer was a beast - 90 ft round the world cat. Aikane X-5 was converted to a between Island charter boat( in face of becoming less competitive - but did break 6 days in a on-record run) and was noted for her "smooth" ride -zero slamming or pounding. Rudy Choy lost his speech in 1995 and produced no further record breakers. I would not give up on "rocker" Aikane-X-5 had plenty of it, and if Rudy Choy were alive and well today- 50/50 his boat would hold the record. I have a "suspicion" (wow I'm going to get smacked around for this one) that the tubular hull shape (resulting in minimal rocker) of modern racing multihulls is more determinded by the pursuit of power/weight than hull resistance (at speed through waves) considerations and certainly "ride" (look at the wakes and spray, not the line drawings). IMUA just had the unfortunate situation of being the wrong water length for Southern California "chop". Yeah it make a "rooster tail" about 20 feet behind the boat at 20+ knots, but whats that? 3.8 x LWL^1/2 on a 29 ft waterline. How about 2.0 x LWL on a 132 foot hull? 23 knots and some jacuzzi bubbles trailing aft is what that is (powered by 2 japanese surplus bus engines...350 hsp each)

What are you describing? An overgrown windsurfer? Maybe. Good luck. I've thought of that- especially with a kite sail.

>Valery this fits all your SOR. Get a kite sail and (2) "blown up homemade" Torqueedo's. It was made with 8,000 lbs of wood (50 cents/lb), 800lbs epoxy (3-10 dollars/lb), 600 lbs fiberglass (1-4 dollars/lb) and a few heavier compononents...$10000 material, 1000hrs (strip plank) labor. "all claims take it leave it". I'm finished defending them to "mga manananggal". Maybe widen the hull beam 25%. You can not find a safer, all around performing cruiser (outside of a "weatherized" large Filipino bangka ).

Aikane X-5 before it lost it's mooring in a storm.

 

Chinaseapirate,thats the idea for pointed sterns at WL, how much rocker did she have? Looks like no accomodations in hulls what were the hull beams

 

well i know the max L/B hull at waterline was "25+" -an article in multihulls. I don't remember if it mentioned the draft. If you blow up that picture you can actually see the slightly rounded deep V shape (very similar to Brown/Newick cross section). It was carried all the way through stem to stern but had a 10 to 12 degree "cant" to it which produces a "symmetrical" leeward hull while sailing. So if you assume 25lbs/ft^3 of block area (that low) and circular section keel line elliptical stern to max hull beam and parabolic bow to same mid point, I figure Aikane X-5's draft at 22-24". He never did offer any "plans" design to him was 90% art. And sure were "pretty" hulls. All his early designs except "foamy" , hardwood keels (maybe he had a Filipino fisherman neighbor), don't know if they were hand carved, laminated or what. I'm sure it had reasonable single berths in the hulls. But it has 24' x 24' multiple berth on the front "trampoline". Just get rid of all that Coast Guard junk and force your kids to learn to swim if you have to. Imua! had a back trampoline also. great fishing spot low and easy to clean. The front was webbing like AikaneX-5 but the back was trampoline material. You could have four hand operated traction kites flying and one helmsman. 8-10 knots "human powered".

 

25 to 1 would mean hulls were 29" max at WL (that s amazing when you look at typ. modern day ratios, you r lucky to get 8 to 1) making it a flex space b4 wharram coined the phrase.

 

The estimated displacement is around 20 000 lb.

You are really afraid that it will be too small!!! Maybe you right, maybe not...

The thruth is that I am afraid to end up too big!!! If it is too big everything gets more complicated, more time consuming, more maintenance, more expensive, etc...

I believe that the Sharpie Schooner 42 that I am working on is just as big as a simple sharpie sailboat can be for its intended purpose.

Will I actually build this sailboat? Don't know, but having fun designing it! If ever a sailboat similar to the one I am designing come up on the market and my life is at the point that I am ready to go on this journey, then I might just buy instead of building. Right now in my life I am not quite ready to go. Instead I dream and I design what seams to be my future sailboat!

The tabernacle are in the plan. Maybe you can't see them but the mast are on tabernacle. The bow sprit is also on a hinge so it can be lifted up.

Thank you everybody for all your inputs. It makes me think about all the differents options.

 

Below the post #96 Atom Voyages outboard well in the lazarette when done . . .

↓ demo video screenshot​

Can be done, but it eats up some cockpit space (which I take as a positive for maintaining good stability when the cockpit is suddenly flooded, as well as for the extra permanent built in flotation aft, done in the same job), so I'll guess it's about what the customer wants...

The below video shows another Atom Voyages lazarette outboard well job, with in that case a bulkhead in front of the outboard.

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Note that in the above video all work was done on the water, in the next video the same boat comes in for a series of major refitting jobs.

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P.S. - Turned out there's a third vid about this boat, about the forward hatch replacement...

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Well, this is probably the most elegant solution!!! A Beta 38 HP saildrive, that cost 18500.00$CAN.... If I go with this solution the engine will be totally enclose in a box. The box will help lower the noise, it will also act as a table and a pedestral to put the cover over the mainsail. The diesel tank will be right under the cockpit floor behind the cabin bulkhead.

This setup should give enought space to work on the engine and all the smell and noise is out of the cabin area! I guess I need to start saving...

I guess the two most expensive part of this sailboat will be the diesel engine and the 8000 lbs lead ballast!!!