1967 Laurin-Koster Ralph Osborne Koster K25, 10 EUR

INTRODUCTION:

I have listed this one under Laurin Koster because it is more well known and Ralph Osborne Koster is less know.
The different is the design: Laurin is more wide, Ralph Osborn is more narrow.
I have been working on this boat for many years, but have not the time to finish it, therefore I am going to give it away to those who can finish it and have the knowledge

To see a lot of images and what has been done please visit our image galleries and use the password: 0000 (4 zero's)

https://wonderfullworld.smugmug.com/Sweden/Yachting/Koster/n-Z8PDbD/Ralph-Osborn-Koster

https://wonderfullworld.smugmug.com/Sweden/Yachting/Koster/Ralph-Osborn-Koster-June-2023/n-689NGB

https://wonderfullworld.smugmug.com/Sweden/Yachting/Koster/n-Z8PDbD/Sailing-with-Ralph-Osborn-Koster


HISTORY:

The boat was bought in Hunnebostrand on the Swedish West Coast.
The boat was made on the West Coast and has been all her life in salt water, which is good for wooden boats because salt prevents fungy to grow in the wood and therefore prevents wood rot.
Wooden boats usually rot away from the top: fresh water entering the deck and so on.


KEELBOLTS:

Salt water is usually bad for iron and stainless steel keelbotls so most boats this age need them replaced. Also stainless steel botls suffer heavily in an environment deprived of oxigen when salt water is able to reach it. They can corrode in a matter of a few years.
The keel bolts from this boat are made of MONEL: Very unique because it was hardly used because of the costs involved using this metal.
( it wil last forever and inspection of bolts which we inside the keelplank and rudder post. proofed this. see also image gelleries)
see below description (chatgtp) what is monel.


CONDITION WHEN WE BOUGHT IT:

The boat looked good when I bought it as you can see in the images, but had hidden problems typical for double ender koster sailing boats.
Originally these boats are not build with an inboard engine.
Later onwards an inboard engine was installed with a propellor shaft using oil pressure to keep the water outside. These propellor shafts usually drip a little oil and water. This mixture ends up in the bilge where it find its way in to the wood via cracks in the bilge paint. The oak wooden keelplank gets wet and does not have time enough to dry before the winder. Oak wood when wet is OK when it gets frozen because it does not get damaged, but the mahogany gets destroyed and this is what happened: all the Mahogany wood was soft which was sitting against the oak wooden keel plank, but only at those places and nowhere else so this was clear: no wood rot. The mahogany was soo soft you could scope it away with a spoon. Previous owner forgot to tell me and I was stupid enough not getting a professional surveyor checking out the boat.

HULL UNDER THE WATERLINE:

Long story short and a lot of investigation did lead to me and a friend, under the guidance of a wooden boat builder to replace the 2 bottom planks over the full lenght of the boat and the ends of the planks above.
You can see this in the image galleries. So right now all bad wood has been replaced.
The hull needs to be sanded down into shape, the planks are still a little thick and you see that above the keel for example (but the lot has been sanded down already)

THE DECK:

These boats were build with a deck make out of planks and in order to prevent leaking the deck was covered in a kind of cotton cloth paintend with a kind of linseed oil based paint with white pigment.
This deck has been totally removed by the previous owner who installed a complete new deck of plywood painted with an epoxy paint. No cracks, no leaking, but the deck needs new paint after so many years.

THE SALOON ROOF:

I removed the cotton cloth: Previous owner was not so smart painting it with a modern alkyd based paint so all paint cracked and came of.
The boat comes with new glass fibre mats and the right epoxy for remaking the roof
All wood from the roof is original and in prestine condition. (as you can see in the image galleries)

COCKPIT:

New wooden panels made for the cockpit seats and panels besides the cockpit/saloon doors (all solid Mahogany wood), made out of glued strips of solid mahogany to avoid cracking in the future. The panels are all cut to shape but not installed, not varnished. (all made by a professional carpenter from Germany) Before using this wood, it was stored in our garage attick. The room is not heated, so the wood never reached furniture humidity levels but stayed at the humidity level good for wood to be used for wooden boats. Wood that has been dried to furniture level humidity will expand too much when used in a marine environment.


THE BILGE:

The metal strips usually screwed on top of the rips need to be installed again. We have the still all, and we also have new (thicker) ones but those need to be cut to size and holes for the screws need to be drilled)
We took them off in order to repair cracks in the rips

The bilge is having new Mahogany on the sides and the oak wooden keelplank has been scraped and sanded.
After long investigation and speaking with other boat buillders we came to the following conclusion:

The issue is: how to avoid rot and how to avoid water getting into the keelplank
Very difficult, but the best solution will be the use of the most flexible paints available: based on Linseed oil mixed with iron powder: probably the best waterproof solution which is also flexible. The old fashioned lead based paints are nowadays forbidden.

https://www.paintpro.se/farg/ottosson-rostskyddsfarg-jarnmonja/


and actually: not using an inboard engine might be the best solution keeping the bilge 100% dry
That should be possible with this boat



PRESENT CONDITION:

If the boat would have been in the water she would have been finished and then there would have been no reason to give her away.
The state in which she is now is best reflected in the 2nd image gallery in the advert:

important aspect: The hull has not dried out too much, hardly any openings below the waterline between the planks
only a few openings between the planks above the waterline.
Very likely that the hull will completely close when in the water (both above and below the waterline)
So very likely no need for so called splining.

The hull under the waterline is covered in a very thick layer (probably many layers) of anti fauling probably containing toxic chemicals not allowed anymore.
This thick layer of anti fauling also helped to avoid the hull drying out too much
But since it might contain toxic chemicals, it might have to be removed and much be done section for section.
Do not scrape the boat at once all: this will dry out the boat and might become a death sentence unless you are prepared to spline between every plank to close the gaps.


WHAT COMES WITH THE BOAT:

The sliding roof and an old sprayhood we still have
The old saloon doors, but we intended to make them form new mahogany wood again, because they do not look so good besides the new mahogany planks we made for the cockpit
The bumper strips from ash wood are removed because they were in a bad condition.
We have new bumper strips planed in the right shape ready to be installed.
We have the mast and boom stored inside the boat tent: they only need cleaning.
The sails are usable but old, stored in the atic of our garage. (see also image galleries to get an impression)
Same for the cushions: in the atttick of the garage.
The engine was stored in the heated part of our garage, hardly used after a complete refurbishment as you also can see in the images.


EXTRA’s:
The boat comes with a very solid trailer (made from a chassis of a truck, so very strong)
but the boat tent has been damaged during last winters heavy snow fall.
Extra Magogany and oak wood (see in one of the images)
Simon CA (extreme flexible and strong glue)
Silika brons screws (enough to change all screws in the hull under the water line. (Bu I doubt if you need to do that)
2 Component epoxy paint for the iron keel. (it needs to be sand blasted first)
Glass fibre mats and epoxy for the roof of the saloon.

and probably more.


COVERED SPACE?
The boat is 27 foot long and my guess is that the boat tent im which it is stored is around 10 m x 5 meters

SUMMARY:

The boat is having massive potential, since all bad wood has been replaced and all other wood hardly shows any dark stains.
In the right skilful hands this boat can become amazing and will be unique: only 2 of this one are build and it is getting more and more rare to find wooden boats in this condition.






KEEL BOLTS FROM MONEL

Monel is a family of metal alloys made primarily of nickel and copper, typically containing about 65–70% nickel and 20–30% copper, along with small amounts of iron, manganese, carbon, and silicon.

Key Properties of Monel

Excellent corrosion resistance, especially in seawater and marine environments.
High strength and toughness over a wide range of temperatures.
Resistant to acids and alkalis under many conditions.
Non-magnetic or only slightly magnetic depending on the specific grade and processing.
Good weldability and machinability (though it can be more difficult to machine than ordinary steel).
Common Grades

Monel 400 – The most widely used grade, known for excellent corrosion resistance.
Monel K-500 – Similar corrosion resistance to Monel 400 but with significantly higher strength due to added aluminum and titanium.
Typical Applications

Monel is commonly used in:

Marine engineering (propeller shafts, pumps, seawater valves)
Chemical processing equipment
Oil and gas industry components
Aerospace parts
Heat exchangers
Fasteners exposed to corrosive environments
Advantages

✅ Outstanding resistance to seawater corrosion
✅ High mechanical strength
✅ Long service life in harsh environments

Disadvantages

❌ More expensive than stainless steel
❌ Can be difficult to machine due to work hardening
❌ Not necessary for applications where less costly corrosion-resistant materials are sufficient

Example

A boat operating in saltwater may use Monel fasteners or shafts because ordinary steel would rust quickly, while Monel can remain functional for many years with minimal corrosion.

In short, Monel is a premium nickel-copper alloy valued for its exceptional corrosion resistance and durability, particularly in marine and chemical environments.