Hoisting day

Now the boat is upright again it is time to hoist some heavy items.

The daggerboard out of the daggerboard case. It was used as a mould for mounting the daggerboardcase slot and since then locked in its position while upside down.

Engine and Jetthruster.

A brand new diesel engine

Today I picked up this Yanmar case at our local Yanmar dealer

With this brand new Yanmar 3YM30 diesel engine inside

Cool !!

No fun to demolish work …

… but sometimes inevitable. It is really an exception if I have to break down components due to an error. But this weekend I did it again. Saturday I glued in the cockpit floor and today I wanted to mount the upright sides of the cockpit and discovered a height difference between front and back of the cockpit floor of 40mm. How is that possible. Temporary fit of insanity? Anyhow, find the differences …

Before

After

Just a few more hours of work 😦

Anyhow, I’ve uploaded some more pictures in the aft cabin and cockpit construction gallery.

Also the foundation for the engine is now finished and awaiting the engine. And I’ve been experimenting with making a drainage gutter for water draining below deck from the Lewmar Flush hatches.

Smoothing out the ride with a thrust bearing drivetrain and overdrive prop

Constant velocity or CV joints are one of those marvels of modern engineering that are exceedingly simple yet brilliant. Known in the engineering world as a “homokinetic” (meaning “same motion”) joint, CV joints are also used in many industries and in the field of transportation

The propeller shaft is aligned to an thrust bearing, which absorbs the propeller thrust. A CV shaft transmits engine power to the thrust bearing and propeller shaft. The CV shaft automatically adjusts to changes in the alignment between engine and thrust bearing and allows engine movements in every direction. 

The primary mission is to support high axial and radial loads while transmitting rotational energy. This means a thrust bearing supports the fore and aft or axial thrust from the propeller, as well as the spinning loads imparted by the rotating shaft, while allowing the shaft to spin with minimal friction.

This way the engine’s motor mounts are no longer compressed by propeller thrust, and, as such, they can be designed much differently than those used for vibration isolation as well as transmission of thrust. Motor mounts that are used in conjunction with thrust bearing systems may be especially “soft,” which means they are considerably more effective when it comes to absorbing engine vibration.  So, by isolating the engine from the rest of the boat, noise and vibration are greatly reduced.

In combination with the two speed (overdrive) Gori prop I hope with this system to have minimized the engine vibrations. By the way, the Gori prop has arrived. Click in the above picture to see the trial fit.

Folding prop or a coffee-table art piece ?

One can not deny that it is a true work of art and a beautiful thing to see in action. Really slick. It’s sort of a hybrid between feathering and folding as the blades swing around for reverse giving the same profile advantage as in forward action. It’s hard to describe the action but the blades swing on an axis perpendicular to the prop shaft. When you go to neutral they fold up like a conventional folding prop. When you go to reverse the unfold in the other direction (they continue swinging from forward-open to folded to reverse-open). You really need to see it (what I can’t resist each time when visiting a boatshow). The prop is a beautiful polished bronze. I’m talking about the Gori 3-blade folding prop …..

Two speed propeller.

My search in the huge array of folding and feathering props has been narrowed down to four potential candidates; Kiwiprop, Maxprop, Flexofold and Gori. There is much to say about these props (and all the others not mentioned here), but I will not do. Being not very scientific and trusting my gut feeling I have examined only these four types in more detail.  I don’t think a feathering prop is suitable for speeds above 15kn and besides of that, the folding type has less drag.  So in the end the real choice is between Flexofold and Gori. No idea which is best and test results in the various magazins aren’t of any help either as the outcomings are so different per test. The Flexofold is cheaper but the Gori is more appealing for my needs, especially the overdrive function for use during windless periods (what is the major circumstances where the engine is in use, I hope) and the power in reverse, which (to my surprise) is even better than a fixed prop.

The Gori look much like any other contemporary folding propeller, with blades that are geared at the base and open on hinge pins. What’s different is that the blades can open in two different directions so that either side of the blade can become the leading face when in forward gear.

The “pitch” of a propeller, which is a measure of how aggressively it bites the water, is determined by the shape of the forward faces of its blades. Gori blades are machined with the hinge pins slightly skewed. When opened in the “normal” direction, the blades have one pitch; when opened in the opposite direction, the other side of each blade becomes its forward face, with approximately 20 percent more pitch. Gori calls this the “overdrive” mode. Putting the propeller into overdrive increases the boat’s speed at any given engine speed. The immediate benefit to the overdrive mode is that the engine runs slower for a given boatspeed and creates substantially less noise and vibration. This results in a 20 percent longer cruising range in overdrive (according to Gori)

Time will tell whether the Gori propeller is equal to the task of maneuvering Fram and bringing her to the desired destination during calm wheather or end up as an expensive piece of art on the coffee table.

Engine.

Revised engine page.

Engine choice.

I am enthusiastic about this Engine which looks very promising.