Sherwood vs Seamax?

A recent question:

I am just learning about these pumps and at 1000 hrs on 330B, my starboard raw water pump began leaking at a rate to great to ignore. So after plunking down over $1600 with California’s 8.75% sales tax for two, if one’s bad the other must be near death right? However after reading your article (Changing the Raw Water Pump), maybe not. I thought I’d read up on replacement. Would you return these and get the Seamax pumps? Do you know if anybody has any real time using the Seamax 1730X? What do think? 1000hrs isn’t horrible mostly in salt water.  My big-block in the last boat needed valves at 1600hrs. I agree that Cummins makes a great engine. In case tractors the Cummins engine is good for at least 8000hrs.



My response:

I had spare Sherwood pumps kicking around when the Seamax was first released.  I considered returning or selling the spare Sherwoods, but decided it wasn’t worth the hassle. When I do install them, I’ll replace them with Seamax. I’ve just heard too many good things about them.

I’m actually getting respectable pump life out of the Sherwoods these days. I still favor Seamax based upon what I’ve been hearing, but my Sherwoods have been doing fine lately.

The only reason I would return your pumps is the price. $1600 is way high. You can get them, or the Seamax pump, for much less.  Personally, I would lean towards returning them.




James Hamilton



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24 comments on “Sherwood vs Seamax?
  1. albert f/v tailspin says:

    our fleet owner bypasses the attitude and cost of seaboard marine seamax smx and buys direct form the manufacturer in korea. same exact as smx. they cant say that it is a smx in writing but it is exact. the company is dj pump in korea. 1/3 the cost even with shipping and customs to florida. smx and tony athens will not want you to know this sorry.

    • I’m sure Tony would prefer that you bought from him but I don’t think it’s unreasonable for a retailer to charge more for a pump than the manufacturer does and I don’t think it’s unfair or unreasonable for a fleet operator like yours to be able to buy direct for these volume purchases. Generally, I’m a pretty big fan of Tony Athens and one of the few things I miss in moving from a Cummins to a John Deere power plant is Tony’s advice. I still like Cummins but after 10 years and 10,700 hours on a Deere, I like Deere even more.

    • Richard says:

      Hi can you provide a contact to Dj pump

      • I’ve used Sherwood pumps and not loved them. I know and like the distributor of Seamax pumps (Seaboard Marine) but I’ve never done business with DJ Pump so I can’t help you on that one.

  2. JAMES WILSON says:

    Does sherwood still make pumps ?

  3. Eric Barclay says:

    would run from Seamax pumps , gears break , 2 cases in 2 years

    • Several have made similar reports. The statistics are starting to speak fairly clearly. Thanks for the posting.

    • john h says:

      Glad to see this pop up on google. As others have pointed out the Seamax is trash and Mr. Tony Athens is a arrogant prick. He absolutely deflects blame to the customer on defective pumps. He got kicked off of that should tell you something. Cash discount at most places means you can write a check, not send in stacks of 100s. beware. piss poor warranty there. ill take my sherwoods any day.

      • Based upon your note and the others, if I was buying a new pump, it probably would be a Sherwood. But, having changed many of the Sherwood pumps over the years, I’m kind of amazed at how poorly they last. The good news is the Sherwood’s just start leaking oil and water rather than suffering a gear or other catastrophic failure mode. I’ll take a leak over a damaging failure mode but I really wish Sherwood would just make the engineering changes needed for the pump last better.

  4. Pete KELLY says:

    Why Cummins/Merc allow these Sherwood defective designed and unreliable Pumps to be fitted to their otherwise excellent engines is beyond me.

    • Cummins, like most marine engine manufacturers, don’t design and build their own raw water pumps so they only have a few to chose from. But, given the volume that Cummins Marine (and partners like Mercruiser) does and how well known Sherwood pump failure mode has become, they really should lean on Sherwood to clean up the design and get it working right or find a different supplier.

  5. Pete KELLY says:

    I’m very disappointed with these Sherwood Pumps. My MercruiserQSD 150HP diesel has only run 190hrs and is now needing a rebuild, all because of saltwater,corrosion and bearing collapse in the Sherwood Pump. The loose pump pulley(because of the failed bearings) threw the Serpentine belt which in turn, chewed through the Cambelt cover and broke the Cambelt. Subsequently Cam/Valve and Piston damage to Mtr.(Mtr rebuild required and very expensive, all because of a defective Sherwood.I’m forced use another Sherwood but will be checking it every at least 50hrs for signs of leakage.

    • I hear you on the pump problems. What I do is watch the weep hole in the bottom of the pump. If the oil seal starts to leak, you’ll see it there first. If the water seal starts to leak, you’ll see it there first. If the bearings start to fail, shaft movement will result, and there will be an oil or water leak at the weep hole.

      I’m not following your failure mode description above. There shouldn’t be a cam belt on a Cummins B-series. They are equipped with a gear driven cam shaft. I check the engine every 4 hours or so listening and looking for any evidence of leakage from any component. Most problems will show up as noise, smell, or leaking before the big money needs to be spent. I understand your frustration on the Sherwood raw water pump design. They last poorly and failures can put other engine components at risk.

  6. James Enterline says:

    On 01/07/2018, I experienced a gear failure of my SMX raw water pump on my port engine while running at 2250 RPM. The pump has 1550 hours on it and was installed on 01/16/2016. I will be contacting Tony Athens today and report back. Please let me know if I can contact you if you have had similar failure. If enough pumps have failed legal action may be required.

    • I’ve not had great success with the Sherwood pumps and have a ton respect for Tony Athens so I expect he will have designed a better pump. Sorry to hear you ran into a problem at 1550 hours but, for what it’s worth, I’ve had Sherwood’s fail earlier. The good news is the failures I’ve seen are just bearings and seals so no other equipment is impacted.

  7. Fred says:

    Having just experienced what sounds like the same failure, I’m very worried about the pump on the other engine

    • Gear train damage is serious and can be expensive so, if you have reason to believe that the damage to you engine was related to the use of aSeamax pump, I personally would be highly motivated to the change the pump on the other engine even if I had to eat the cost of replacment.

  8. Tim Conners says:

    Warning! Do not use the Seamax pumps! I learned the hard way. My sherwood pump on my cummins 6bta was going thru impellers. I replaced it with an expensive Seamax pump. After around 1000 hours the teeth on the drive gear sheared off. This damaged the gear on my cam so now I’ll need to pretty much rebuild the motor. I purchased the seamax pump from Tony Athens at Seaboard marine. It was only 15 months old and the warranty is advertised as a “no hassle 2 year warranty”. When I contacted Tony at Seaboard marine, he will not take responsibility for the pump or damage to the motor. He is coming up with all kinds of lame excuses trying to blame the installation or the cam gear. Since this happened, I have spoken with mechanics who have seen this before. It’s not worth risking your engine. It’s much better to just change impellers more often and even change out the sherwood pump occasionally

    • James Hamilton says:

      Tim Conners story of timing gear damage afer installing SeaMax pump is a tough one. There are many possible causes of gear train damage not all related to pump design or manufacturing issuses. I’ve not heard of other any other faults potentially related to these pumps but, since I’ve since switched to John Deere power I’m not watching as closely as I used to. Timng gear damage is not not a common failure mode and it certainly is an expensive one so this one story is a concerning one. Sorry to hear about this one Tim.

    • stranger says:

      i have had three seamax shear gears in two years and know of others that did the same

      • My only personal experience is with Sherwood pumps. My take on the the Sherwood pumps is they generally perform poorly and fail frequently. The Sherwood pump failure rate is not enough to make me dislike the Cummins engines but it sure would be nice to not have to change pumps as frequently.

        I had great hope for the Seamax pump being an improvement on the basis of my confidence in the skill and experience of Tony Athens. However, the experiences relayed above by Stranger, Fred, and Tim Connors are enough to keep me from using or recommending Seamax. Thanks for your comment.

        • allan query says:

          The Sherwood pump is guaranteed to fail in salt water due to water seal failure and subsequent bearing failure. Both my Sherwood pumps failed at ~4 years in salt water and 500 hours The SMX pump addresses these issues as best as possible within the physical space limits. My SMX pumps are 4 years old and doing fine so far. Are there others who have issues with the SMX pump?

          • I’m with you Allan. I was pretty unimpressed with the Sherwood pump and over 4,100 hours on two Cummins B-series engines I replaced the Sherwood pumps fairly frequently. I learned about the Seaboard Marine SMX 1730 ( around the time I sold the boat so I’ve never tried one of them personally but I do know the Sherwood’s are poor, I’m pretty impressed with Tony Athens, and I know he was as annoyed with the Sherwood pump as I was. There have been a couple of posts here from folks using the SMX pump reporting problems but, without all the Cummins hours Tony’s customers do, I would expect the SMX has become a very good alternative.

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