Hurth HBW 50 R2 gearbox removal

[GrahamW]

Boat is 34 foot, built 1962, all wood, 8 tons displacement - pic attached.

Engine is a Perkins Perama installed 1993. Almost certain that the gearbox was installed at the same time. No problems before now in current ownership of 8 years.

[GrahamW]

Sorry - pic now attached as per previous post.

[highseas]

Wow! nice boat Graham.Its as old as me.The other problem with Hurth transmissions is when they sit unused.The bearings sit above the fluid and rust.When storing boat its recommended to fill transm. to top,to avoid this problem.I would just get the ZF10,its about the same price,and alot easier to find.They call them the $1. an hr. transmission.

[sailr69]

Originally Posted by highseas

Clutches for starters,then the thrust washers.I rebuilt my HBW50 at authorized Hurth rebuilder 5 years ago in San Francisco.Finding parts then was almost impossible,finally did though.Lasted 900hrs.The 50 is discontinued,the ZF6 was the replacement until about 1 year ago,now it is discontinued also,and now the ZF10 is the standard replacement model.Did everything right .Always in reverse under sail,changed ATF every 100 hrs,fully in gear in use,babied the thing,as it was my second.Now about to install ZF6.Going synthetic this time.

I was checking transmission temperature often and found the trans was getting too hot in my engine space, not enough ventilation, heat is the reason for early failure. they offer a water cooler which bolts on the trans in a prepared spot for it. after installing the cooler, the temperature stays within the specs for this trans. when changing oil, it should be the same red it was when filled. brown means overheat. without the cooler, reduce speed until the trans cools down. check temperature with a cheap laser unit from harbor freight. $25 or so

[highseas]

Good advice sailr,I have the laser thermometer now.I religiously change fluid,with this latest unit I will use synthetic.The cooler sounds like a good idea.But the duty cycle must not be overlooked.

[highseas]

Sailr,I was curious how many hrs. you have on that 21 yr. old transm. ?

[Antonio Martin]

I have a Universal Diesel m25xp engine WITH A HURT TRANSMISSION, in a Catalina sailboat 30, when I give it advance takes long time to React and almost eats the whole race of the lever, however, in reverse enters instantly, as I can adjust it to enter the advance immediately? can you helpme

[FPNC]

Hello Graham, Start right from jump street when you are replacing this transmission. Some engine builders are notorious for installing a cheap transmission that is not rated for the engine hp/torque or application. Make sure the transmission is rated for a diesel application and rated for the number of cylinders, the HP@maximum RPM and for a displacement vessel. If you are brave enough to replace with a ZF product, do not use the pleasure craft ratings.

[Uncle Bob]

Originally Posted by Antonio Martin

I have a Universal Diesel m25xp engine WITH A HURT TRANSMISSION, in a Catalina sailboat 30, when I give it advance takes long time to React and almost eats the whole race of the lever, however, in reverse enters instantly, as I can adjust it to enter the advance immediately? can you helpme

Been there done that, replace it with a PRM and use the boat without worrying how long will the gearbox last this time.

[PappysSailing]

Hello,
I realize that most of these posts go back quite a few years, however, was wondering if anyone has ever heard of a foreign made, Baysan 30, trans as a replacement for a burnt out Hurth HBW 50 ? Been sold here in the U.S. for about three years now. Factory in Turkey but they may actually be headquartered in the Netherlands, not sure. Dealer is in U.S. Same bolt pattern and height as the hbw50, but need to move shaft aft about 1 1/2 in.
May hook this up to a Universal 25 XP in the Catalina 34. As the name suggests, specs allow for up to 30 h.p. input. Price got my attention. Appreciate any info. Pappy

[FPNC]

According to the Baysan company web site, the Baysan 30 transmission is not pleasure duty rated for 23 hp @ 3200 RPM. You would be better off with a small PRM or Twin Disc transmission. Which will be less money than a ZF.

At your engines 3200 Max RPM, the Baysan 30 is only pleasure duty rated at about 18 hp. Baysan does not define what 'pleasure duty ' means. ZF does not consider a sailboat application as 'pleasure duty' and also apply a 15 -25% reduction for 'shock factor' on engines with less than 4 cylinders. Your original HBW 50 was not even rated for your engines HP & Torque and application.

Transmission ratings are based on the your engines hp @ max engine RPM. In this case the 25XP is 23 hp @ 3200 RPM. This way of rating transmission capacity factors in engine torque. Torque is what destroys transmissions. Again, according to the Baysan website, the Baysan 30 transmission is only max rated for 22-23 hp depending on ratio and at a much higher 4000 RPM.

[PappysSailing]

Thanks for the shot, interesting info, especially on the under sizing of the hbw 50 for the 25 XP, but re Baysan, I think that you were looking at the specs on their M 30 "C" model. The M30 shows these numbers:

BAYSAN M30 MARINE GEARBOX (MECHANICAL) (30HP, 22KW).

Cheers, Pappy

[FPNC]

No. I was looking at the M30

English | M30 | Baysan Marine

The wording is a bit confusing but the graph plainly shows that the rating is less than 20 hp at 3200 RPM. Max power is stated as 16 kw which is 21.44 hp.

Power factor is .55 or .58 hp per 100 RPM, Depending on ratio. So the 2:1 ratio at 3200 RPM would be 32 x .58 = 18.56 hp. The 2.5:1 ratio would be even less.

They call it a 30 hp gear but the actual numerical ratings and graph don't reflect that.

The M30C ratings are only marginally different.

Transmissions are the weakest link in your system. Don't scrimp on capacity. Don't use ZF pleasure ratings for sailboat applications.

[PappysSailing]

FPNC,
Yes. I now see the different ratings in the spec sheets n sent an email to info @Baysan asking for an explanation on this this wide discrepancy.
Thank you for your insight on this. . Pappy

[PappysSailing]

FPNC,
Sorry no follow up. Sent two emails to Baysan Marine... no reply. Maybe it's a language translation problem. Who knows. Haven't bought anything yet. Pappy