Sharpie Schooner 42 with an outboard motor

Don't give up.Write Beta letters demanding they give you a 12hsp version for $6,200.00. That I would buy. Have all your friends write letters too. Get them all stamped by Trudeau. Them put the smallest 38 prop on it!

 

There is no particular reason to use lead ballast on these boats. Find a fabricator and collect their steel punchings. Make a mold and encapsulate them in cheap resin. You might want about half a ton of lead for trim ballast that you can hide in small crannies. Get that from big tire shops. You can melt down the weights on the grill and pull out the clips. Also check with any industrial motor rebuilders. SS motor shafts make nice ballast, and you can sometimes buy them in significant quantities.

 

Most automotive tire weights are now zinc in the USA, which is a significant reduction in weight (37%) over lead. It is easy to melt into shapes and I use it for rudders and centerboards. Steel (cast, rolled, iron, etc.) is only a 30% reduction, though a bit harder to machine and shape. I've used steel and stainless steel ( slightly heavier then regular steel) cut into plates, which were stacked to form ballast and if you're handy with a torch or can get your hands on a plasma cutter, you can shape them fairly easily including bolt holes, etc.

 

Tungsten is as heavy as Gold, but a lot more difficult to work with, but one could start collecting light bulb incandescent filaments, those you can hammer to near solid into a mold, and then encapsulate them with molten lead, which alas is much lighter.

Think of lead as an investment for when retiring from boating, it's the only part of the boat that keeps increasing in value.

 

what is the reduction for black "sand" that you can rake off beaches with a magnet broom?

 

Anybody ever tried to use a submersible motor, the one used in well pump for an electric drive? I am thinking the kind Grundfos makes for its sumersible pump. I guess it will only need an adaptor to install a propeller.

Grundfos Submersible Motors https://ca.grundfos.com/products/find-product/submersible-motors.html

 

Most submersible pump motors are intended to drive an axial pump, a healthy motor might be 2 HP and will cost several hundred bucks (just replaced a 2 HP 12 stage motor/pump assembly in my well). It'll be 240 VAC single or 3 phase, which is a lot of electrons to suck from batteries.

Ballast will be one of the easiest things to gather and assemble on a project like this, regardless of material chosen.

 

@PAR

I get OEM pricing on those Grundfos pump and motor because we use them quite a bit at work. Could even get a drive to control it.

Let say that I get 15hp motor, combine with a 7.5hp diesel generator combined with enought battery capacity to provide for the other 7.5hp. When cruising around the generator power the motor at 50%, When I need full power the battery kicks in. Other scenario when I am just going in and oio of the marina I can just use the battery at 50% and when I need full power I turn on the gneerator.

Might be a good solution to look into!

 

If you take the anti-ventilation plate the propeller will ventilate and generate no thrust. You may hate them, but they are part of a sophisticated design you don't seem to understand. Your disrespect for professionals, that actually know what they are doing, does nothing to make you look good. Seems like a typical case of the sour grapes.

 

You are overcomplicating things, which is a bad thing for cruising. Keep it as simple as possible. Before picking a size for the generator and batteries, do an energy audit for your needs.

 

The OP asks a simple question. One that I know you could answer better than me, and yet, no real answer. No potential sale... lead customer to a predefined route that may produce a sale later.

@valery gaulin . Yes, maybe. If its 1800 RPM great. See if the drive can convert to 3 phase AND adjust voltage, I wouldn't know. Battery "capacity" normally provides an energy storage not a power rating but in this case with the (proper type) speed controller and 6 Walmart deep cycle batteries (29D-$80each) wired in parallel you will have enough juice to not overheat your batteries and run your motor approximately 40 minutes at WOT (7+ knots) with the generator out of fuel or 60 minutes with it fueled and running. If you cut back to 1/3 throttle that is 2 hours of silent running at 5+ knots, and indefinitely with the generator on. You need an inverter $1200 (non marine) or equivalent marine ($? ) 12,000 Watt continuous rating, (2) 20 amp continuous battery chargers ($40), some switches, some battery terminals, some wire and probably a relay rather than two extra switches. You will save battery life (as in alive or dead - not low), and diesel by bypassing the charger/battery/inverter, but you will only get about 5hsp to the motor and have to live with the noise. Word to the wise - go slow and charge batteries dockside. I have 10hsp air cooled diesel generator and it says 5000 watts, it cost $600 in 2005. Speeds shown are conservative because discussion of magic props are inflammatory and apparently imply a disrespect to those who won't to allow access to them. It would be better if the motor in question had a composite body and wires dangling elsewhere. If it is 3600RPM or higher even just find a used forklift motor and a thru hull drive shaft bearing and make it waterproof. 1800 is still too high RPM for magic props.

 

A simple question isn't always answered with a simple answer, and often the questioner lacks the basic knowledge to understand the answer.

In those cases the questioner and companions need a comprehensive study of the topic at hand before being able to understand the given answers.

Also simple questions are often based on wrong assumptions to begin with.

So the answer needs to start with cleaning up the wrong assumptions, which the questioner and companions aren't able to understand due to their lack of basic knowledge of the topic at hand.

In those cases the answer needs the text of a book rather than a post on a forum.

So the internet turns out to be no alternative for a solid education and actual experience, one still needs to study to grasp the on a forum given answers, and the findings of search engines.

However, the internet enables it to search and ask for study material, but then it still needs to be studied to understand what it's all about.

If want to improve a design (e.g. a boat or an outboard) then one needs to equal or surpass the knowledge and experience of the designer, or there will be a big chance once build it turns out to be much worse than the original design, all due to not grasping what's going on.

 

This is absolutely wrong. Using Peukert's equation you can easily calculate your actual available power output depending on the current draw.

How do you propose to get three phase from DC, fit all the necessary equipment in the volume available, and make any economic sense?

 

I'll think it needs the electrical know how of Tesla, Inc. + a lot of marine technique knowledge and experience to build a better than ready off the shelf available electric marine propulsion system.

 

>Angelique. So what then? Are you supporting Gonzo's solution, that after he got wet by improperly mounting an outboard engine and starting it while the prop was partially out of the water and the ventilation plate had been removed, of attempting to lynch the mechanic for going against his advise, the same one who had previously told him in so many words that the new propeller would not affect any harm to the engine.
As I'm even still writing the above dribble shows up. I think it best if Gonzo explained elsewhere which "professional" he believes I'm disrespecting. I must have have missed a comma or something. Battery capacity is an energy rating measured in amp hours. I was kind enough to allow the OP to figure out for himself whether he cared to refine his description of current draw other than using "capacity". As two the question of what the OP's drive is capable of, I'm not proposing anything. I provided the parts list, biggest item is Valery's proposed generator. The heaviest may in fact be cheaper than equivalent "ballast". The motor would go on the keel section that was cut out relieving your concerns affecting the performance of the design. The propeller...no RPM in the user's guide stated, so without a known source for reducing RPM, looking grim to put the 21" prop in. Maybe there is just no support for repealing the ridiculous mandatory helmets law, here on this site, which started a long time ago in a galaxy far away...IDK