K Plane Swap 380 vs 280 42' Cigarette Hull ??
 

After 33 years I thought I would treat my boat to a new set of K-planes. The existing TAbs are 280 series-about 20" long. They are used extensively as we have twin CAT Diesels with Twin Disc Gears & Arneson Drives . That is a lot of weight in the rear, so the tabs are needed to keep the bow down, especially in rough water. The 380 series K Planes are about 30" long, so obviously there will be some differences. However, I am thinking with this size boat ,, 42' X 10' 6" X 20,000 lbs, the bigger the better. Does anyone have any experience with a boa this size running 380 K Planes? I realize most OSO owners are running boats much faster than mine (top speed 42 knots) but any qualified input would be appreciated
https://cimg3.ibsrv.net/gimg/www.off...cec30a9a80.jpg
https://cimg3.ibsrv.net/gimg/www.off...6612eff41b.jpg

I replaced my 280's with a pair of 450 Interceptors and they are superior in every way. For a boat like yours I have a feeling you will get a big improvement in planing out and low speed handling, and a definite MPG improvement.

Zipwake | Dynamic Trim-Control System

Time to get into the 21st century.

You can send me a PM if you want to discuss by phone or something. I am really happy with them.

Change the 280 plates out for 380's.. very simple pull the pins and replace -- hopefully they are not too corroded as they can be a PIA to come apart--- the 380 will work much better for your boat and you will not need as much tab to get the same effect as the shorter units... Judging from your transom I would not change the mounting plates as you might get into a bunch of work that you were not expecting or wanting. If money is no object there are all kinds of things you can hang off the back of a transom... Good Luck! I always liked those Diesel Cigs.

It's a no brainer. It will be a different boat. I had 48" tabs on my old 36' Cig race boat. And I just doubled the size of the tabs on my 55 Sunseeker.

I doubt if it will be an issue at the speed you run but some caution would be prudent.

If I recall correctly, there are some differences with the pins depending on how old the tabs are.
Mbam???

I would be interested on what the differences are and what year they changed. I would like to to switch to 380s also, currently using 1992 k planes.

We just had the bottom glass-blasted to remove years of paint (and reveal all kinds of dings), so the K planes are completely removed. Since everything is removed, we are gonna just buy the entire kit #841945A02, which includes everthing needed including pumps. It will cost more than just the tabs only, but I will feel better with everything being new. We have already filled all the holes, which were showing some wear and rot (after 33 years) so we will re-drill the transom when the new tabs arrive. Any thoughts on what paint/primer to use on these new tabs?
https://cimg6.ibsrv.net/gimg/www.off...0191823819.jpg
https://cimg2.ibsrv.net/gimg/www.off...6290b9eece.jpg
https://cimg6.ibsrv.net/gimg/www.off...c5865d0e54.jpg

Here are the K planes. All the ones with A suufix are old style, A0 are new style.

https://www.mercruiserparts.com/trim...nd-component-1

For example
A01 = new style = https://www.mercruiserparts.com/bam/...32085/8504/383
A1 = old style = https://www.mercruiserparts.com/bam/...32085/8504/380

You can identify old/new by looking at the cylinder. The new version has bushings in it kind of like a trim ram. The old version does not.

Thx for that info Marc. I assume u r a vendor and supplier of mercruiser parts? I did see listed a kit WITHOUT pumps. Is that everthing needed outside of the transom? How much is that (for both sides) as opposed to the kit that includes the pumps?
The prices dont show freight. What is approcimate freight to 21842 in MD? Do u charge sales tax when shipping to MD? THX again

Yes we are a vendor.

The complete kits are here https://www.mercruiserparts.com/k-planes-accessories

No tax outside of FL, and if you purchase during the lock down I will ship for $75 flat to a freight terminal or business address (continental US). They really are too heavy to ship safely via UPS, we would ship by truck.