Reviewed the several attempts made to ensure a leak free jet installation. Decided waterjets have so many potential leak paths might be a good idea to fit a bilge pump.

Had a suitable pump salvaged from a scrap electric garden sprayer. Original idea was to activate the pump using the water alarm, but decided that was too complex at this stage. An automatic action might also obscure the leakage rate and negate desires to maintain system redundancy.
Have now installed an alarm as one feature and can activate the pump with a second RC switch. Once trials are complete, may revert to making this pump automatic. Hope by then to have gained enough confidence in the leak correction.

Another change was to replace the horizontal flat styrene panel, added earlier to accommodate the waterjets, with a perspex one. Can now observe the jet operation without dismantling. Once did this to another model, it does aid troubleshooting.

Spring is approaching and the ice has largely gone, so tried the first open water sail. Objectives are to check and see if the leak treatments worked dynamically and try all jet movements in actual operation. Will also give an insight into the ballast and waterline relationship.

The temperature was only + 3C, but thought a double layer of woad would provide enough thermal protection. The last visit to our site showed no ice, but we had forgotten the effect of wind!
A northerly wind had blown a thick layer of ice into the dock. Fortunately, there were several inches of open water alongside the dock edge. Enough to do many of the planned maneuvers.

Was able to establish:
1) Base ballast requirements and that the waterjets worked. They move a lot of water and suspect the model will be overpowered. Might be better with 2 not 3S power.
2) The reverse operation and linkage work.
3) The cooling system works, although the bilge pump requires priming first.
4) Leakage rate was lower than expected and the water alarm not activated. Seems the sealing efforts have achieved some success.

Waiting now for the ice to move out so can resume with the more ambitious tests.

Beautiful sunny day with a strong onshore breeze. Considered the model would drift inshore if it failed, so decided to try it.
The water surface was too rough to accurately establish if the ballast changes were correct, but if not they seem close.

The waterjets work well. Plan to try a 2S battery next time, as think 3S tends to overpower.
Rough water made it difficult to examine the waterjet action. There is plenty of power and the bow wave, even on one jet, is higher than scale.

The foredeck was loose fitting, allowing considerable water ingress.
Had adopted the suggestion from another modeler to fit a coffer dam ahead of the jets. This contains jet leakage in the stern area where it can be drained by the bilge pump.
However, water splashed under the foredeck collecting in the hull forward of the dam, into an area where the pump does not reach.
Was surprised just how much water had collected in the forward hull, significantly affecting the waterline.

Also, could not confirm if the impellor rotation was correct. I like to use the Tx ”Elevon” steering function, although this tends to disguise the rotation commands. Determining rotation even when the propellers can be seen is rotating is misleading, when hidden it becomes even difficult.
Tried adjusting the Tx functions, but the wind and waves obscured the effect. Back on the bench determined one was reversed. Now corrected.

Would like to retain the convenience of Elevon control where both screws are controlled by one Tx lever. Wondering though if it would be better to control waterjets by the more traditional twin lever set-up. Planning the next test to explore this.

One problem with waterjets is that there is minimal reverse function. Reverse is usually achieved by redirecting the flow using a reverser bucket.
Also, the control reaction to reverse the model with the lever does not work. Trying to think of a way to overcome this.
Currently, the reverse bucket needs selecting first and then motor forward again. No longer intuitive. With practice this might become easier to remember, hope so.

Have reached a point where can conclude this year’s test program. This will allow building to restart next winter.

Points are:

1) Installed a 2S cell, which proves to be more than adequate. The model is controllable and has adequate speed, sufficient to produce an excessive bow wave.
2) Had spent some time trying to locate and resolve leaks. This has been successful and leakage, whilst still exceeding conventional vessels, is not unreasonable.
3) The audible water leak detector was effective, but irritating. Once the bilge pump had removed any water, it stayed on until the hull had dried. Am going to replace buzzer with flashing lights. I can then see when water builds up, but others do not hear it. Not so obtrusive.
4) Cooling system works.

Have tried and adjusted every system, and am satisfied they work properly.
A boating buddy, Garth took a video which has just been posted in the Media Gallery. It shows the model in action. It also shows my lack of dexterity with waterjets and reverse bucket selection. And, in this installation, their rapid response.
Model now drying out in storage until winter. Obviously last blog for a while.
Can now concentrate on sailing other models rather than building!

Now the sailing season is essentially over, time to get back to writing this blog.

Had a nagging suspicion the waterjets were still not quite right. Decided on another set of water tests to confirm.

First, as the lake was nice and still, left the model quietly floating by the dock for around 15 minutes to check for leaks. There was no water ingress from the jet installations!

Once underway, there was slight ingress from around the perspex panel installed in the inner stern. Nothing to be particularly concerned about as it was quickly drained with the bilge pump. See picture.
Will reseal when it is removed for finishing and painting this winter.

When observing the waterjets began to suspect one was still reversed. This might seem obvious but I use a single lever control for both motors, with the Tx Elevon control system. This makes establishing rotation difficult as the impellers are not visible.

It was. Anyway, easily corrected. The already acceptable performance has improved noticeably.

The jet performance is good and maneuverability using the nozzle steering controls only, quite satisfactory.

All need to do now is figure out a way to operate the reverse buckets automatically when the throttle control lever moves to the reverse part of the gate!

A Shapeways bow thruster unit was installed. I used the mid-size unit to replicate the size on the vessel.
It works well, but the amount of thrust generated is low and easily overpowered by windage. Would have been better to have used a larger version.

Have some ideas about using a larger motor to increase torque and reduce the speed drop when operating in water. Not likely to get this completed before next Spring though. Anyway. want to do all the other finishing touches first.
Also, used a cheap brushed ESC for the motor control as this is not a primary propulsion unit.
Found the modulation to be disappointingly poor. It immediately went from to speed forward or reverse and was difficult to settle at the mid, null point.
Rather than replace with a better item have used another Tx channel to provide a master switch for the bow thruster function.
After much investigation found the ESC was for brushed, but the motor was a small two wire brushless! Chinese websites are light on detail. Decided to leave as is. Cannot find a small, light brushless ESC and as it works best to leave along.

Started to add the finishing touches.

First added the navigation lights. These are behind the masking tape on the forward superstructure in the second picture. Spent ages trying to decide where they were on the real ship and finally stumbled across a picture where they had been left on in daylight. The coloured lights could be discerned behind a clear lens designed to minimize radar reflections.

Decided to leave the radar support structure, radar and short mast off until the painting was complete. The wiring and switches had previously been fitted.

The dazzle camouflage paint pattern takes careful replicating. Would have been assisted by detailed plans, but these are not available so had to rely on internet pictures.
There are many pictures, however, the pattern dimensions have to be estimated. Ended up with quite a reasonable facsimile
Now painted, the model is starting to look interesting. Quite amazing what paint does for a model!

Like most warships, this class has evolved during service. There have been many changes to both profile and layout.
Decided the best information showed the final vessel, K35 “Karlstad” this appeared to include the updates. Adjusted the model to replicate her.

A contact in Australia put me onto a local decal manufacturer, who makes a sheet of decals for this model at this scale,
Decided, although could make up my own decals with a local manufacturer, by the time all was complete would have saved little. Would also have to produce the artwork myself.

Purchased a sheet from Australia in early Spring. It was in dry storage, in a sealed plastic packet until just before this blog was written. Suspect the months in storage might have caused a deterioration in the decal adhesive.
As it dried the occasional corner started lifting. Slipped a small amount of canopy glue using a craft knife into these areas and the problem was overcome.

Curious to know if others have found this issue with older decals.

Once the decals were fitted and the adhesive dried, coated the model in a matt clear aerosol spray. Apart from the obvious improvement to a more realistic finish, this reinforces the decal adhesive and seals from water ingress.

Have been postponing work on the gun, radar ranging aerial, main radar mast and rear deck fencing. These items are not straightforward to construct and will be covered in future blogs

Working sternwards from the bow, started to make the outstanding details.

1) The deck gun. The several plans accumulated gave a good outline. Original thoughts were to make the front turret door open, releasing the gun barrel when opened. After some head scratching and abortive attempts, decided at this scale not only would that detail be difficult to discern, but even more difficult to reproduce. Decided to make the door static and paint the aperture gap on.

2) Gun ranging radar. Have not found any specific drawings for this feature and, examining the various ships in the class, realized it varied between them. Decided to make the best facsimile, but make it removable. If better plans materialize can replace.

3) Main radar mast. This is essentially a cone that supports a small radar, but contains other hidden stealth features. After numerous attempts to make the cone using styrene sheet by hand or shaping inside a funnel, nothing seemed to work. Wanted the cone to be hollow so could fit a small radar scanner. One of my shipbuilding friends suggested his Grandson could 3 D print it. Made up a sketch and from it he made a great, robust and stable cone. Fitted a small, geared motor inside to drive the scanner and support the navigation lights. Very few pictures show the lights and they did change between vessels. Have reproduced the ones fitted to Karlstad.

Was going to include the rear deck railings, antennas and helicopter in this blog but none are coming together quickly. Will make a future blog update as completed.

Was dreading making the rear deck railings as, using brass tube (for the most robust installation) requires much structural soldering.
The railing can be operated to both vertical and horizontal positions to facilitate helicopter operations. This means a system of hinges is required.

Determined the sizes of brass rod required and made up a crude jig to locate components as needed.
The first railing (stern as the smallest) turned out quite well, but none thereafter!

Had changed the soldering iron tip to a new, pointed one as the earlier spade shaped one was worn out. After much messing around and resoldering finally arrived at the combination that worked. My objective was to leave a shiny, small gob of solder on each joint. This is much harder that it sounds!

Thought a pointed tip would concentrate the heat, then used a max. setting for maximum heat. That it might well do, but does not give a good joint. Often came apart with poor adhesion and left a poor surface finish.
Eventually determined, for this 1/32” rod and 1/16” tube joints, the best combination turned out to be;
With a 60w soldering iron. About half heat (250 C), a new tip with chisel end and very thin multi-core solder. The tip was cleaned frequently to remove contamination.
Once arrived at this combination things moved quite well. Did not require as much cleaning up either to remove excess solder. The components are held together and the solder flows into the joint. The chisel tip also helps to hold the joint together as the solder flows.

Made the hinges out of styrene, cut them into a “C” shape so the bottom rail could be slotted into the groove allowing the rail to rotate. The railings go all around the three sides of the rear deck, as they are shaped around the stern corners the side bottom rails can be inserted into the rear, forming a discreet stop.

Next, tack soldering brass mesh into the frames to resemble netting proved another challenge. First attempt was to cut small pieces of mesh and tack into the apertures.
This looked unsightly, any tacks that were not perfectly symmetrical looked awful when painted.
Next tried to CA glue the mesh in. This also looked unsightly as any CA residue leakage then blocked adjacent mesh holes and, when painted, looked odd.

Found the best way was to cut a strip of mesh and cover all the apertures at once. Then used CA glue to hold the mesh in place. Appreciate this is cheating to the purist.
Either that or hurl these railings and convert to a conventional stanchion and rail design. As used on some of the earlier vessels.

All fitted and looks acceptable.

The helicopter was straightforward.
Cheated by buying a Revell AW109 kit and converting it resemble the Swedish forces version. Fastened it down with a central restraint to mimic the “Bear trap” helicopter landing system. Modified the blades to allow them to fold rearwards for storage, as is done with most ship borne helicopters.

The more powerful bow thruster motor had now arrived. This motor is slightly bigger so the gears no longer mesh. Wanted to purchase a new set from KK Produkcja, in Poland where had purchased the original ones. Tried to place an order, but they ignored my several messages. Eventually ordered through Aliexpress.

In the meantime. Rummaged through my stock of defective servos to see it there were any gears that might work. Came up with a pair that fit quite well and seem to mesh properly.
Doubt this bow thruster will ever have enough power, should have chosen the larger version. Also replaced the ESC with one that can be modulated so removed the extra electric switch.
Pity cannot test these modifications until winter passes. My wide dispensed with our indoor test facilities last year!

Antennas

There are two antennas fitted to the front of the superstructure. Made these up from old wound guitar strings, with mounts made from old plastic model bits. The strings are flexible yet substantial. Once painted they look realistic.

The model is now essentially finished. Did one last bench test of electrical systems and all checked out.

This entry thus closes the blog. This project was my introduction to the use of waterjets. They do present some challenges and advantages compared to the traditional propeller layout. Have decided they are worth persevering with, my next model will be equipped with them too.