90hp in a 35'?

I came across an ad for a 34' CHB trawler equipped with a single 90hp Mercedes diesel. I haven't been able to find any manufacturer's information concerning the original equipment. So I'm left to ponder two questions:

Is it likely that this was the OEM engine?

Does 90hp sound like a reasonable size engine for this much boat?

Have an 80-horsepower diesel which readily moves a 14-ton, 35-foot, fat boat up to hull speed, with some power to spare.

Thanks. I'm still trying to get my mind around just how little power (and fuel) it takes to move these things!

PPandE said:

Thanks. I'm still trying to get my mind around just how little power (and fuel) it takes to move these things!

Click to expand...

It doesn't take much to move a boat slowly. It's when you want it to go fast that it starts to require a ton of power (and correspondingly fuel).

Takes about 1.7 gph at one knot (6.3) below hull speed (7.3 at 4 gph).

I am sure you have researched, I did a short search and all the ones I saw advertised had Lehman's 120 hp. I have noted a number of references to a Mercedes 190, I'm wondering if the lister got the specs wrong. I can't find any references to a Mercedes 90.

Greetings,
Mr. PP. I think a TF member (Ms. Donna) has a Taiwanese boat with Mercedes power. You might want to get in touch with her.

RT Firefly said:

Greetings,
Mr. PP. I think a TF member (Ms. Donna) has a Taiwanese boat with Mercedes power. You might want to get in touch with her.

Click to expand...

Thanks! I will.

I highly doubt that it is the original engine. Probably came from Taiwan with a F.L. 120. IMHO 90 hp will do the job but might come up short if you are fighting a headwind or a following sea or get recruited into doing some towing.

Water skiing and tubing are out of the question.

pete

Benford 38 Fantail. Westerbeke 55hp.

0.75gph at 7kts.
1.5gph at 8.3kts.

I've never understood the need for massive amounts of horsepower in these types of vessels.

As others have said a 90hp diesel is enough for a 35 foot trawler, you'll probably cruise 7-8 kn easily.

What I'd recommend doing research on is parts availability for the Mercedes. Almost every old CHB I've seen had the Ford Lehmans. I know that there are few old Mercedes out there but I think they're rare, at least in North America. On an older boat you should expect to need to replace parts. Also, if you have a mechanical issue away from your home port, the more common the engine the easier it will be to repair.

Mine is a 45' boat (50' LOA) with 135 HP engine. 7 knot cruise is 2 GPH (40 HP). Pretty easy to push a boat at 6 to 7 knots.

Ted

OCD ( or boat poker ) Do you have any trouble climbing big head seas or going upwind ??

My Manatee is a fat, windy 36 that came with a Volvo 90. The first dozen or so Manatees built were offered with a 55 Perkins which did cruise at hull speed. My boat has been repowered with a Yanmar 140, but anything over 100 HP is a waste IMO.

90 hp is plenty for that boat. But the bigger issue is that you won't find much support for a Mercedes diesel in the US.

David

Mercedes support is a concern. I plan to check with some automotive suppliers as well as marine. There seems to be quite a few cars of that vintage running around.

I’m shopping in the under $50,000 market now. If I don’t find something suitable there, I’ll bump it up. Also trying to find something East of the Rockies.

Thanks all.

Benthic2 said:

OCD ( or boat poker ) Do you have any trouble climbing big head seas or going upwind ??

Click to expand...

At the RPM the engine is running, it can produce about 80 HP. This gives the engine the capacity to easily maintain the RPM when driving into seas. If less HP were available at that RPM, it might have more trouble maintaining RPM when hitting waves.

The propeller diameter and shaft were from the old engine which was 450 HP and could push the boat at 14 knots. The 28" diameter propeller was chosen to utilize all the 450 HP. Simply, when you're only using 40 HP through that propeller, there is almost no slippage regardless of headwind or seas. In 3 to 4' seas, I loose a few tenths of a knot. A slight increase in RPM would generally overcome that, but I usually don't bother.

Ted

Parts and parts price The usual ROT , rule of thumb is 3 HP per ton (2240LBS) to cruise at a rational speed.

Ton is displacement weight , not the volume ton on the boats hull plate.

THe engine mfg love to claim 20HP from a gallon of diesel, but that's with a perfect match of engine tranny gears and prop. Figure 15 HP as a ROT.

ROT for Non industrial diesels, the engine usually can produce 1 HP from each 3 cubic inches of displacement for very long service lives..

Simply hearing the fuel burn and knowing these 3 ROT will give a good idea about the choice of engine.


Parts and parts pricing , more popular engines are easier.

Pete Meisinger said:

Water skiing and tubing are out of the question.

pete

Click to expand...

Water skiing at six knots sounds a lot like trolling for sharks.

Hi all! Mercedes engine owner here!

1986 marine trader, original Mercedes 166 hp engine documented and registered historic.

Parts? Yea a bit difficult but not impossible. It’s really an old Mercedes tractor engine if you want to get technical. Sometime I need to get creative.

Sips fuel! Extremely efficient even with the turbo.

Been doing a bunch of cosmetic work on her

And of course the photo is sideways. Sorry guys!

Donna said:

Been doing a bunch of cosmetic work on her

Click to expand...

Looking good, even if she appears to be down in the bow.

Ted

Willard 36 with Perkins 4.236 around 75 hp. Full displacement and ballasted and weighs close to 30k lbs. Perfect sized engine. A smaller engine, say a Perkins 4.108 (50hp) would be underpowered in head seas, which are common on the pacific coast, her home waters.

Donna said:

Been doing a bunch of cosmetic work on her

Click to expand...

Beautiful, Donna! She looks great!

My Willard has 37hp in an 8 ton 30’ boat.

I am used to mercedes marine engine

PPandE said:

I came across an ad for a 34' CHB trawler equipped with a single 90hp Mercedes diesel. I haven't been able to find any manufacturer's information concerning the original equipment. So I'm left to ponder two questions:

Is it likely that this was the OEM engine?

Does 90hp sound like a reasonable size engine for this much boat?

Click to expand...

Hi
I am former MB diesel instructor and i participate to the marinisation of Mercedes Benz industrial and truck engines in Brazil. I was a fishing fleet owner for many years and own 11 boats all with Mercedes engine they are very economical 180g/hp/hour an hard on the job They use to work trawling heavy shrimp net 24/7 just stoping to check oil. And run around 20k hours before overhall.
It wasn't an OEM it was a factory engine
Give me you engine model number if it is a 6 cyl should be OM 321 Olders probably this one with 90 HP at 2400rpm There was also OM 352 yougers 105 HP at 2800 rpm OM 352 T (turbo) 165 Hp at 2800 rpm and then OM 366,mostly turbo 366T with 200Hp at 3000 rpm I have the specs and everything you need to know. About parts especialy the OM 352 and OM 366 you can go to a Freightliner dealer ( Fl 80 use MB 366 engine , older truck 1413 use 352 ) and have truck motor parts.(oil filters , diesel filters all dealers Bosh diesel injection shop for Pump and injectors and oil filters)
For the marine parts on it,you can import from Brazil or find some dealers there that have those parts (i can help you finding)
Saddly they where tier 1 as all engines of that time and Mercedes quit marine engines because of cost getting tier 2 and then now tier 3 In my opinion they where exceptional midles range diesel marine engine ( you have also the 4 cyl OM 324/OM314/OM364)
If you want to contact me directly magipati@yahoo.ca
Have a great day, keep safe.
Michel

First post. Caroline has a 94 HP Cat 3304, burns 2.2gph at 1300 rpm and 8.2 kts through the water. She weighs 44 tons wet. Not bad for a 53' boat.

My Manatee has a 100 hp engine, I’ve heard that Krogen figured out 35hp is all that was needed. I don’t know if they installed higher hp engines, 55-90-100 110 because of engine manufacturers stock or to please the buying public.

SCOUT has 2x54hp - 40ft overall, 50,000lbs. ~2gph @7kn.