double universal joint to connect the drive shaft to the engine

[deeper]

I've just gone through this exercise. Short story - engine mounts are easy to make. Hull chopping and re-laying is isn't.

[drcat]

As far as cutting/reducing size of the supports. Assume supports are wood covered with layers of fiberglass.
Take a look at Sail Life you tube from about 4-6 months ago. The owner of this Warrior 38 was faced with rotted wood stringers/ribs covered with fiberglass. Most recommendations would have had him cutting out the rotted wood, replacing stringers and ribs with new wooden ones and fiberglassing. Instead owner consulted marine architect and instead ended up adding more fiberglass that replaced the strength of the wood.
Reason I mention is that it may be possible to cut down the size of the wooden/fiberglass supports for the engine to make way for a larger engine, but bring the strength back to the supports by added layers of fiberglass. How to deal with the oil pan. Depth of oil pans are done for several reasons- clearance of crankshaft and amount of oil for adequate oil cooling, volume of oil needed to suspend combustion products and reach oil change schedule and depth for pickup of oil when heeled. If a less deep oil pan would meet both crankcase clearance and oil pickup needs when heeled, the other issues can be solved with a separate oil sump with oil filter relocation kit.

[wingssail]

Originally Posted by Bill O

...Not really certain why you or others need to charge around doing hull speed under motor, but like most sailboats they can sail faster than they can motor...

Seriously asking this?

Many sailboat owners these days do not actually like to sail much. If the wind comes up, they take the sails down. When it comes time to go home from a day sail, they roll up the genoa and motor back to the marina.

And heaven forbid that they have to sail upwind.

So, since they operate the boat as a motor boat, a big motor improves the boat, for them.

[Andy F]

Hi
Our yachts previous owner had uprated the engine and fitted a ‘python’ drive. Think it comes from Uk. Google it, it seems to work fantastically not noticed any issues. Touching wood.

[Bill O]

Originally Posted by wingssail

Seriously asking this?

Many sailboat owners these days do not actually like to sail much. If the wind comes up, they take the sails down. When it comes time to go home from a day sail, they roll up the genoa and motor back to the marina.

And heaven forbid that they have to sail upwind.

So, since they operate the boat as a motor boat, a big motor improves the boat, for them.

Wasn't really a question per se. (maybe more of a comment/reminder)

And yes, I've observed the same thing as well as sailboats getting towed in when they couldn't start the motor w/plenty of wind to sail.


Bill O.

[skenn_ie]

A boat, under sail, is a lot more comfortable in a blow. OK, it will be heeling a bit more, considerably more, but it won't roll nearly as much as a motor boat or even that boat, under power. A long keel is even better, but again, under sail. If you are new to sailing, if you are beating, each leg is sailed relative to the wind direction, (maybe 10 degrees off the wind, in some cases 20 or 25degrees depending on the boat), not where you want to go. Going where you want to end up, is achieved by averaging your port and starboard tacks. Forward movement through the water is what stops you going sideways as the keel isn't a brake, it is a wing.

[carlwk3c]

Originally Posted by Northbound44

A general engine guideline for yachts with a displacement hull is the weight in tonne multiplied by 4 hp.
Before replacing your engine and spending big money , I would personally considering to check if your propeller have the wrong pitch, size or design. The lower pitch makes the engine reach maximum rpm at slower speeds. Conversely, a higher pitch will deliver greater top speeds, but slower acceleration.
A quick test you can easily do is,after warming up the engine, try to know what is the maximum RPM you can actually reach by doing a short test. If according your engine specs, you cannot reach the maximum RPM, your prop pitch is too high. On the opposite, if you can go over the maximum RPM, it is too low.
The number of blades and prop diameter should also match the weight and underwater drag characteristics.

Here is good links on the subject:

https://www.pbo.co.uk/gear/choose-ri...ler-boat-62058

Are you over-propped? - Ocean Navigator - January/February 2017

I’m thinking the same thing. Prop pitch. I had a 50hp Perkins in my Tayana 42 and that was plenty. 75 hp seems like it would be more than needed for your boat. What’s the current engine? (If you stated,?i missed it.)

[GrowleyMonster]

A 16hp Beta should push your 30'er okay. Along with many others, I agree that you need to optimize your prop. A fixed prop cah be changed easily enough in the water. A folding prop should be changed on the hard, IME.



I have seen a couple of setups where there was actually an auxillary sump to enable the engine to sit lower. I honestly don't like such a rube goldberg bit of shade tree engineering but as long as it works, it works, I guess.


I would prefer CV joints over major surgery of engine bedding components, anyway. CV joints will be more durable and efficient than two U joints.



If you do not motor a lot, you might well consider a series hybrid setup. Install your new engine with a generator, and use an electric motor or two motors for actual propulsion. You could go with two ME-0913 motors belt driving the prop shaft. Or a single electric car induction motor. The nice thing about electric is you can go with an oversize motor with no significant efficiency penalty at low power settings. You have no minimum idle speed, either, so you can ghost around your marina as slow as conditions allow. You have instant power available, if you also add a battery bank, which I strongly recommend. That gives you twist-the-knob instant torque for power tacking and similar maneuvers while sailing. For a day sail you might well not even have to start the diesel, just recharge from shore power at the dock. A typical 30'er does just fine with a 48v system. Higher voltage is more efficient but calls for different electrical standards. A series hybrid system is not as power efficient as a regular diesel installation but it can be fairly close. With a battery bank, you can run the diesel at its optimum power and speed settings to charge, and run the drive motor at whatever speed you require. This is not a simple thing to set up and may not be worth it, but I would give it a look if you are having doubts about other solutions.



Are you experiencing any unusual noise or vibration? Any heat to speak of, in line shaft bearings, or transmission? Visible shaft wobble? How old is your Cutless bearing? What sort of stuffing box are you using? And is it allowing any water to pass through? Is the diesel in good health? Plenty of compression, no excessive smoke? Check that compression. Fuel filters and lines in good shape? Lift pump working properly? Injectors inspected recently? There are a lot of mechanical issues that could be preventing your Beta from achieving and transferring full power, especially if it is more than one thing working against you. Verify, don't assume, that the engine is actually getting enough fuel. A differential pressure gauge across the filter is a great upgrade. A pressure gauge in the lift pump discharge might be a good idea... knock on wood, I have never installed one on any boat of mine. Collapsing rubber fuel lines can restrict flow. Make sure you are getting plenty of air, too.



Does the engine run well with the transmission in neutral? Try slowly advancing the throttle to full rated speed. If not, you could have a timing or valve or some other internal issue.



What is your reduction ratio? You can check this easily enough by marking the flywheel and the prop shaft coupling, and turning the engine over with a breaker bar while the injectors are pulled and the fuel shutoff is closed. If it is some odd or unusual figure, that could be the issue. For instance, 1:1 would likely cause your prop to cavitate severely at over 2000 RPM and load the engine a lot more than what your prop and hull combination would suggest. Something in the neighborhood of 2:1 is what I would expect to see.



Lastly, IMHO too often we tend to solve our problems by adding more power when the better option would be to not proceed in the face of adverse conditions and avoid situations where insufficient power would place the boat in jeopardy.



And final lastly, try different props first, before doing anything. Something isn't right. My elderly 4-107 at somewhere around 50HP pushes my fat and heavy 44'er fairly well. Too well for me to want a 75hp engine, in a boat a good bit heavier than yours. I believe I displace around 14 tons with a 13.5' beam.

[Old fella]

Mate, there is a cheap and easy way, I've several of my boats, just cut down the cradle to the size you need, little motors take bugger all holding up, then get piece of 4 x 4 angle iron to fit between your engine beds, weld a plate on each end to bolt to the beds, cut a hole for your prop shaft to go thru, stick thrust bearing on it. Then get a car or small truck drive shaft, cut the guts out it then weld the two ends together, matching flanges for prop shaft and gear box, and bobs your uncle, oh and don't worry about a bit of misalignment, universals don't like to be to straight. Also take no notice of the bs about running at high revs just so long as you got some load on it, as I said I've done this several times, never had a problem, no vibrations, smooth as.

[Pete7]

Originally Posted by Old fella

Mate, there is a cheap and easy way,

I would suggest the cheap and easy way is to sort out the prop so rather than max out at 2500 rpm, it achieves full revs for the engine at 3600 rpm. This boat had an engine swop from a MD7A which is 12hp but only revs to 2600 rpm, so was the prop changed after the engine swop? It could be as simple a problem as this.

The boat is listed as weighing 3500 kgs empty. From experience of our 31ft yacht we have 500 kgs of fuel, water, dinghy and stuff in cruising mode. So the Freedom should weigh in at 4T, you couldn't carry much more on a 30ft yacht. 16hp will be fine.

Pete

[GrowleyMonster]

Another thing... when you pull your prop, if the pitch is not stamped on it, measure your pitch. It isn't that hard. Lay it on some paper or poster board. Mark the center of the hub on the paper. Mark the distance from center to the widest point of a blade and draw a circle of that radius. Use a small square with an edge resting on the paper to mark the circle directly under the leading edge of the blade, and again at the trailing edge of the blade. Then measure the height of the leading edge of the blade from the paper, and the trailing edge.



Next, with a protractor measure the angular distance between leading and trailing edges. Divide by 360. That is what part of a full circle a single blade spans. Let's say just for the example you get .125. Subtract the height of the trailing edge from the height of the leading edge, or vice versa. You just want the difference in inches. Divide that difference by the part of the circle, which is .125. Let's say that difference was 1.5". You would have a pitch of 12". Or very close to it. Next time you are on the hard, see if the shop will let you borrow some stamps, and then stamp the pitch and diameter on the face of the hub if it is not there already. The pitch is an important piece of data when comparing props.


When the prop is off, you will likely see a lot of damage to the leading edge in particular. You can take it to a prop shop or if it is not that bad you can dress the edges yourself with a file. Naturally you want to knock off any barnies growing on it, and polish it up a bit. A clean prop is even more important than a clean hull, for its size. The hull only moves at around 5kts or so but the prop, well I will let you do the math but it is traveling a LOT faster.


If the prop is bent, take it to a shop. Unless you are stranded on a remote island, you don't want to mess with straightening it yourself when you can let a pro do it. Also, YMMV but I like to carry a spare prop. Stuff happens.

[Old fella]

Originally Posted by Pete7

I would suggest the cheap and easy way is to sort out the prop so rather than max out at 2500 rpm, it achieves full revs for the engine at 3600 rpm. This boat had an engine swop from a MD7A which is 12hp but only revs to 2600 rpm, so was the prop changed after the engine swop? It could be as simple a problem as this.

The boat is listed as weighing 3500 kgs empty. From experience of our 31ft yacht we have 500 kgs of fuel, water, dinghy and stuff in cruising mode. So the Freedom should weigh in at 4T, you couldn't carry much more on a 30ft yacht. 16hp will be fine.

Pete

The man was asking about putting a bigger engine and ideas how to achieve this, and you all are taking him for an idiot and talking about props which he probably already knows about. It's great to have excess HP, 30 years ago I had a 28ft ferro Hartley motor sailer, took out the 10hp Stuart turner and put in a 40hp bmc, the boat would hull speed around 5.5 knots, I would sit over 7 at 1500 revs, and no matter how rough it got it still sat at that, so I'd be in a nice calm bay hours before my mates on there yachts. So next time your out there getting the crap kicked out of you, turn to your wife and crew and say we could have in shelter hours ago, but I'm real sailer, and see what she says.

[BBill]

I just read this string for the 1st time and think you are looking in the wrong direction with an engine change...at least as the first option. The best answers have already been given and it's a prop change. Dial in the prop to max rpms before you go cutting and changing engines. Running that Beta 16 at 2500 rpms is giving you 12-13 hp. The extra 3 hp you get at max rpms is a game changer on that size engine. Your boat isn't too big for 16 hp unless you are clawing off a lee shore in 30kt winds or shooting inlets with breaking waves. Leave 2 blades to the racing crowd and go 3 blade. If you want to see how little difference there is in drag between the two, drag something that equals the area of a 3rd blade and see if you can measure or tell the difference in speed. But the point is your prop is way out of spec no matter how many blades.

Off the shelf props are a "best guess". See if you can find anyone with spare props to try...then take the best one to a prop shop and have them add/subtract diameter and/or pitch. That's what I do and it usually take 2-3 times to get a prop truly dialed in.

[Katrinu]

Originally Posted by Bill whitmore

The solution to your problem is Thompson Couplings made in Australia. Study their website. I have used their coupling For many years with great success. Excellent design

Hi Bill
Is there some one particular at Thompson to contact please?

I need to eliminate Cardan joints on both inboards and a have a down angle of 10 deg .

I have lots of vibration.

Thanks

[Cheechako]

One thing I learned in the development of a boat was that U joints require and angle of... something like 4 degrees or more. They dont like to use them straight with no angle.