Hello All, I restoring a Coronet 21DC.

The boat was originally born with a 4 cylinder engine, but the previous owner put a 5.0l volvo penta v8 in instead. Unfortunately he did not do a very good job...

Either way my issue here is the engine mounts. The previous owner had glued two wooden beams in the bottom which the engine would stand on. These beams have now rotted away and are not suitable anymore. Does anybody know how the engine mounts are supposed to look for the v8 engine in a 21DC? I understood that it is a stainless steal 'beam' kind of structure? I have searched the archive in hope to find a drawing of the original engine mount but without any luck.

I hope somebody can help? Or has drawings of an engine mount?

kind regards

Frederik

Hello All, I restoring a Coronet 21DC.

The boat was originally born with a 4 cylinder engine, but the previous owner put a 5.0l volvo penta v8 in instead. Unfortunately he did not do a very good job...

Either way my issue here is the engine mounts. The previous owner had glued two wooden beams in the bottom which the engine would stand on. These beams have now rotted away and are not suitable anymore. Does anybody know how the engine mounts are supposed to look for the v8 engine in a 21DC? I understood that it is a stainless steal ''beam'' kind of structure? I have searched the archive in hope to find a drawing of the original engine mount but without any luck.

I hope somebody can help? Or has drawings of an engine mount?

kind regards

Frederik

Hej!

Tror aldrig 21 DC utrustades med V8 från fabrik, men jag tror i stort sett alla eftermonterade står på tvärgående stålbalkar - rostfria eller galvaniserade. Min V6:a är i alla fall monterad så. Har ingen ritning, men kan ta en bild senare i veckan.

You can find a drawing in the archive if you search under 21 Sunrunner. The file name is 7-11-360.jpg . My boat came with such a beam. It was in a rather poor condition and as I put in a 300hp engine it was decided to install full length wooden beams, properly treated and glassed in, instead of making a new beam. I think this will be both stronger and significantly cheaper than fabricating a steel beam.

On the drawing you will see in hand writing 21.4, which is the internal model number at the yard.

https://www.archive.coronet.nu/?to=1&ID=

PS. The original engine was a 225 hp V-8.

Thank you for your reply Mats and Jan.

@Jan, do you have any pictures of how you installed full length wooden beams? would you suggest to install wooden beams instead of the metal one?

kind regards

Junior

Frederik, I searched my pictures and attach some of them giving you an idea of how a design with a front steel cross beam can look like.
I have an VP AQ271C, 275 hp. It was mounted in my boat 1990.
The engine is supported by a steel beam welded from two U-beams so that the centre part under the engine sump is lower than the side parts, where the engine rubber mounts are mounted.
The beam end plates are fixed with two bolts on each side, port and starboard to the existing longitudinal beams in the hull.
I sand blasted and repainted the beam when the engine was removed due to a rusted sump in 2005. The design works fine.
Return if you want some more details.
Regards, Johan

picture 2

pictuer 3

Not easy to show with photos - the engine is in the way! But here is a try with port side first and then starboard:

Starboard:

OK, a few pictures more! The reason longitudinal beams were chosen as a basis for my installation was the recommendation from the boat builder who helped me with the engine installation. I think this method is also the most common way of doing it. With regards to recommendations I would prefer to give you the pros and cons as I see them.

Longitudinal beams: Easy to do yourself and probably much cheaper if you do not weld it yourself. You can easily extend the glass work to make a nice new surface in the engine room. Correctly engineered at least as strong as a steel beam. Should last the life of the engine if properly glassed in. Easy to reach far aft in the engine room.
On the negative side it is a bit tricky to reach under the engine for cleaning but not too bad.

Steel beam: If you have one it is a much quicker installation and it probably makes sense in a boat yard where you can have them mass fabricated and share them between several boat models. And it si ov course very elegant! somewhat easier to clean under the engine.

So both ways will do the job and your circumstances will decide what to choose.

The link below leads to a 6-part miniseries about an engine change. It is in swedish but the films are at least in part self explaining. I bought my engine from the same yard very lightly used without knowing about the films and it is actually my engine being mounted (the seller told me about the film!) but that is another story. You can see that their boat has longitudinal beams.

https://www.hamnen.se/batkunskap/batagarens-gor-det-sjalv/motorbyte-ge-din-bat-ett-nytt-liv.html

Picture 2

Picture 3

Picture 4

Hej
Ska montera in en V8 i min Coronet 4 De luxe. En hel del plastjobb först. Kommer bygga upp enbart med glasfiber, firet mat och polyester som flera har rekommenderat. Har tänkt mig längsgående balkar i bred plyfa som plastas in som motorbalkar.

Är i princip klar med rensningsjobbet och en 5,7 l Mercruiser med Alpha drev väntar i garaget. Hoppas att det ska gå bra.

Hur långt bör motorutrymmen vara? Måste såklart flytta fram "torpedväggen" något men hur långt rekommenderar ni?

//Jörgen, Växjö

Hello All,

Thank you all for your feedback. Great to have all your help so that i can figure out what is best for my setup!

@Jan thank you for the pro''s and cons. after carefull consideration and my lack of welding skills i have chosen to make the longditudinal beams. I will take some pictures as my work progresses and upload it here.

@Jörgen my 21 dc has been modified for a 5.0L v8. And those engines are of the same size. I will measure my engine bay and let you know how far you should move the ''firewall''/torpedo.

kind regards

Junior