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Old 24-10-2009, 07:13   #1
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I Be One o' Ya

Well boys, (and girls):

I am really one of 'ya now. I closed on a 1982 Mainship 34. Engine= replaced in '06 with 250 Diamond Cummins. Turned over 200 hours during sea trial. I spoke to the mechanic after the purchase that installed and he said the rebuilder sent him a rebuilt block that was cracked so they sent him a new one. He added that he had to tune it down because with the skeg it it got squirrelly at WOT. Hull not designed for 20 knots. Hope for 3-4 gph @1800RPM 12 knots, but I hope for a lot of things.


Has a 2:1 tranney and seems to run really good. The mechanic ask what I paid, when I told him he said, damn, they have spent that much in the last 3 years.

Has a new 3.5k NextGen also. Raitian does not work, no water heater, no holding tank, bridge deck needs a peel and rebuild...it leaks, needs a buff and wax, ground tackle upgrade, bottom job, new HVAC, electrical and electronics. Stand some redecor and other clean-up but even with all that done I will come out with less than $50K purchase and refit. At least I hope to, however I hope for a lot of things. I am capabible to do much of the work. Any suggestions gratefully accepted about the refit or whatever.

I am in a quandry bout an inverter, mosified sine or true sine, much difference in price.


Wife came home, after 7 month furlough, said buy a boat, so when she retires in June we can head out. Leaving in Fl. for refit, will end up eventually on Texas Coast.


Anybody want to buy a Bennington 22' tri toon?

Da Mule
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Old 24-10-2009, 07:28   #2
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Congratulations Mule !!!
I’ll be very surprised, and very pleased, to learn that you can get 3-4 mpg (3-4 gph @ 12) from a 34 footer, on plane.
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Old 24-10-2009, 07:31   #3
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Congratulations!
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Old 24-10-2009, 09:20   #4
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Hey Mule...thats great.
How about some snap shots of your new baby?
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Old 24-10-2009, 09:38   #5
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I am in a quandry bout an inverter, mosified sine or true sine, much difference in price.

True sine wave is better for sensitive electronics such as computers and TVs. If you are just running a microwave, and maybe a laptop power supply the square wave should be ok. I have a shuttle PC that has refused to boot right a couple of times on my Square wave but most of the time works ok. So it all depends. If you can afford it you are better off with the true sine wave. When you install it remember to have all a separate neutral buss for the inverter loads or all kinds of weird things will happen. Also only use a unit UL approved for marine use. Oh and figure out your loads and needs ahead of time so you will size the unit correctly.

Good Luck
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Old 25-10-2009, 13:28   #6
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Originally Posted by Mule View Post
Well boys, (and girls): I am really one of 'ya now. I closed on a 1982 Mainship 34.
Congratulations you're almost there!

To truly be one of us you'll have to start doing your own repairs.

... always one more layer to the onion.
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Old 25-10-2009, 14:35   #7
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Congratulations you're almost there!

To truly be one of us you'll have to start doing your own repairs.

... always one more layer to the onion.
I have not had her long enough to get started. As it stands now I wil pay for a bottom job because of restrictions. 3 tranducers need only one, and I have it so 2 holes plugged. there are no blisters after coming up on 30 years in '12, not of these boats seem to have blisters. I hope to put copper coat epoxy antifouling system on.

Bridgedeck I will do myself, inverter install I will do myself. Redecking with cork or PlasTeak, myself. New head (or raising the old one), holding tank.. myself. Garmon suit of electronics...myself. I am here with the boat and my truck is riding low with tools.

I cannot help but wonder why toilets for marine application are only what seems like a foot off the floor. I feel like a frog getting ready to jump with my knees above my shoulders.
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Old 27-10-2009, 13:10   #8
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The toilet should be elevated to a more comfortable height then. On my boat, it's directly above the holding tank, and that gives it enough height that my feet can't even reach the floor. I can't lower without reducing holding tank capacity. Raising your toilet, I expect, is a lot more do-able.
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Old 27-10-2009, 14:33   #9
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Sounds like a good boat. Going through much of the same on an old trawler myself....
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Old 06-11-2009, 13:17   #10
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You'll be able to get 3 mpg at displacement speeds -- think 7 knots. At 12 knots, expect 1.3 nmpg. Flat out, expect 0.9 nmpg.

Since it sounds like you like hot weather, I would suggest you just use painted sand non-skid. The synthetic teak is VERY hot underfoot: expect 150 degrees in the sun on a 90 degree day. It really starts to melt the soles of your shoes!

If you want the look of teak, I suggest you go real teak. Its much, much cooler than the synthetic teak decks. There are people in Florida who make teak decks bonded to sheets of fiberglass that they ship to you and you just glue it down to the deck.

However, there are several bad thing about teak: if you spill greasy food on it, it stains. Its expensive. Its heavy. And you can only clean it using low pressure water (your thumb on the end of the hose). Brushes wear it out, high pressure hose fitting wear it out.

All of these disadvantages apply to the synthetic teak too. Well, maybe you can use a higher pressure hose. But its still so soft that it wears out quickly. And as it wears, it looks more and more cheesy.

Painted sand is easy to do, wears well, is good non-skid, and is easy to clean and maintain. Get very white sand, as darker sand makes the deck look dirty as the paint starts to wear out over the sand grains.
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Old 06-11-2009, 13:43   #11
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Congrats on your new boat! Now get to work!

There are some articles on your boat on the internet. You will probably want to have a look at those. One article has your boat getting about 1 gallon per mile at 10.3 MPH (What can I say? ..sometimes even boat magazine authors boat don't know boats speeds are measured in knots.)

Its a semi-displacement hull, so it never really planes. It rises up some but mostly pushes a lot of water to the side. On the other hand, a semi-displacement hull will give you a better ride than a full planing hull. Its not going to happen that you will get 3-4 MPG on a plane.

http://www.powerandmotoryacht.com/0300mainship43/
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Old 06-11-2009, 16:20   #12
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David,
I am not sure how much semi vs plaining hull I have here. At 13 knots she leaves a very, very small wake; at speeds going up to 12-13n she throws a pretty good wake. It has a 17 +- dead rise that flattens out in the back. She is a single engined prop protected, rudder protected skeg boat. Seems like at 15 knots she is a plaining (planeing?) boat but at 7-8 knots, displacement. When I get it off the hard after the bottom work I will punch back in here and give a better evaluation.

This is a single 34.

Hobart
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Old 06-11-2009, 16:58   #13
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WTG mule!

WTG Mule !! I just KNOW your gonna keep her down here, right? Close by so we can go fishin', right? I can pop fer some gas and grub..

Like David said...you better get to work! You know mama's gonna want that thing ready on time...

Seiously, though, where on the coast d'ya have in mind to go? Let me know if i can help...
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Old 06-11-2009, 17:09   #14
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David,
I am not sure how much semi vs plaining hull I have here. At 13 knots she leaves a very, very small wake; at speeds going up to 12-13n she throws a pretty good wake.
Hobart
With all due respect, it seems most people with powerboats underestimate the size of wake they throw and the effect it has on other boats. I know when we had a stinkboat, er, ah, powerboat, I certainly did not appreciate these things. Of course that could have been due to the lack of age/lack of wisdom factor also.

We saw one of those tugs last year, Nordic Tug I think it was? And the guy was just hounding on it, huge bow spray, clouds of black smoke and a massive wake. The boat is trying to plane but can't, and the wake at that point is like wind against tide. Keep 'er down to 7 knots, you'll love the fuel economy and we'll love the smooth ride.
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Old 06-11-2009, 18:04   #15
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David,
I am not sure how much semi vs plaining hull I have here. At 13 knots she leaves a very, very small wake; at speeds going up to 12-13n she throws a pretty good wake. It has a 17 +- dead rise that flattens out in the back. She is a single engined prop protected, rudder protected skeg boat. Seems like at 15 knots she is a plaining (planeing?) boat but at 7-8 knots, displacement. When I get it off the hard after the bottom work I will punch back in here and give a better evaluation.

This is a single 34.

Hobart
Semi-planing hulls are jsut that: they are designed to exceed hull speed but not to become fully planing, where the boat is essentially supported by dynamic forces (lift). All boats are more efficient at less than hull speed (the speed of the wave that's the length of the waterline, so 1.34 x sqrt of the waterline length). On your boat, when you are going about 7 knots, you'll be pretty darn efficient, like any 34 foot waterline boat.

As you go faster, the drag goes up more and more, until its very high where your wake is very large. That wake is the drag: its taking a LOT of energy to make those waves!

As you go a bit faster, and the wake diminishes, you'll be in the sweet spot of a semi-planing hull, where the drag will still be much more than at 7 knots, but it will be less than a pure planing hull, and it will be less than a displacement hull. If this is the speed where your engine is also making peak torque (which means it is generating the most HP per gallon of fuel burned), then you will be as efficient as you can be above hull speed. Its not really planing, but the shape of the stern allows the stern wave to move well aft quite easily, sort of as if your waterline length was much longer than it really is. But the boat won't really raise up out of the water like a true planing boat.

When you go faster, your bow wave will start to get bigger, and you may find the boat starting to get squirrelly, as you seemed to suggest happened at 20 knots or so. At this speed, a full planing hull would have much less drag, because the full planing hull would be being lifted from the water, reducing the wetted surface. The reason semi-planing hulls get draggy at higher speed is because they don't really plane, so they don't get the reduced wetted surface.

So: a boat at displacement speeds is efficient because the amount of energy going into wave making is low, and the amount of energy absorbed by surface friction is low, simply because the speed is low.

As any hull goes faster, the wave drag increases, and the wetted surface increases, so all boats see a dramatic drag increase as the speed goes past 1.34 x sqrt of the waterline length.

A pure displacement boat with rising buttock lines aft (like a sailboat) will allow the stern wave to get huge, and lots of energy gets absorbed (drag increases a lot).

A semi planing boat has a temporary advantage because the flattened stern shape allows the wave to get longer without getting much higher, so wave drag does not increase as sharply, but surface drag due to wetted surface keeps increasing.

A planing hull, once planing, may see a decrease in total drag once fully planing (about 3 x sqrt waterline). And assuming the drive train is efficient at high horsepower (e.g., outdrive, pod drive, surface drive), the total drag may remain constant at any increasing speed until aerodynamic drag starts to dominate. This is because as speed increases, the lift increases, so less and less wetted surface, and less and less wave drag, where the reducing effect of speed happens to be the same as the increase in lift as an effect of speed. In practice, one only sees these constant low drag figures on high performance boats. More typical boats have substantial wind resistance, shaft and strut drag, non-horizontal thrust, prop tunnels, and other characteristics that increase drag rapidly with speed.
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