Buying decision, Turbo or Not ?

[Mappy]

Hi All

We have decided to buy a Californian 34 but we are not sure about the engine size/hp we should get. One of the primary uses of the boat will be to tow one or two 24 ft sailboats to various regattas, delivery distances of 5 - 8 hours each way. These sailboats only weigh 2400lbs and are easy to tow but*will only tolerate being towed at 7 - 7.5 knots. The question is will the 4-236 engines be large enough and*conversely will the T6-354 engines be underutilized and off turbo boost rpm range at the 7 knot speeds.

Any input on what rpm the turbos run at 7 -7.5 and is that too low an rpm for long term use.

Do you think the 85hp 4 cylinders will be over worked?

If you have any fuel consumption numbers*either engine*for this speed range that would help too.

Thanks for the help

Roger

 

[Nomad Willy]

Mappy,
The drag of two 24' sailboats will be VERY small unless you try to go faster.
I'd choose the smaller engines but I personally like to power a boat w only 10 or 15% power above what's necessary to drive a boat at the desired speed. I think the Californian is a semi-planing hull that could utilise the power of the bigger engines but if you don't actually use that power the engines will be underloaded. You'll probably need to burn about 10 gph to load the bigger engines over 50%. I'd go w the smaller engines. Normal fuel consumption for the small engines should be about 2 to 2.5 gph per engine. More information like displacement, pictures of the hull out of the water, gear ratios and beam would help firm up what I've just said or change the predictions. Sounds like your'e buying a new boat but I didn't know they were still made.

-- Edited by nomadwilly on Tuesday 9th of November 2010 09:59:34 PM

 

[Mappy]

Nomadwilly
Thanks for the input. We are going to buy an older Californian 34 of the 77 - 84 years. But there are 15 of them for sale*on the west coast with engines from 85 hp each to 210 hp each, so there is plenty of choice. I didn't do the numbers for displacement (18000lb), beam (12.4 ft) etc, since this is Californian forum I guessed all that would be common knowledge. I do tend to agree with you on leaning towards the smaller engines.

More feedback from Cal 34 owners would be most welcome.

Thanks
Roger

 

[Marin]

I don't know anything about Californians, but you might want to think hard about smaller engines. You can always run a larger engine at a lower power setting but you can NEVER get more power out of a small engine if you need it.

Since a Californian is (I assume) a semi-planing boat, I would think it would be beneficial to have enough power on board to take advantage of the boat's ability to go faster than hull speed. You never know when that capability might come in handy.

I've stated my philosophy plenty of times on this forum--- there's no such thing as too much power in boats or planes (or cars for that matter). Obviously that's dependent on the hull being able to use the extra power.

I've related an instance in our marina where a fellow ordered a new Grand Banks 52 with smaller-than-standard engines. His reasoning was the same as we see posted here from time to time--- better efficiency, lower fuel burn, better balance of power to cruise speed, etc. In the end he came to greatly regret his decision (and still does). The boat's lack of power has frustrated him no end, and worse, it's not been a popular boat in the GB charter fleet because of this.

Another downside to this particular installation is the lighter-than-normal engines messed up the trim of the boat and he ended up having to have some expensive*major surgery on the decks to correct drainage problems.* Don't ask me why they didn't correct the trim issue with ballast--- I don't know.

There is a fellow on this forum named Carey. You may have seen posts of his. We boat with him and his wife quite a bit. He has a 36' custom lobsterboat with a 420 hp Cat in it. The boat's designed cruise speed is in the neighborhood of 15 knots. Starting a few years ago when the price of diesel shot up he began cruising a tad faster than us, perhaps 8.5 knots. At this power setting his fuel consumption went way down. He monitors the engine's temperature, and every run he operates the boat at its "proper" power setting for awhile to "clean things out." He also operates at speed in rough water where his hull does a lot better at 14 knots or so than at 8 or 9.

Now Carey's boat could be pushed along at 8 knots very nicely with less than 100 horsepower. But he would totally lose the ability to go faster in rough water or in a situation that requires him to run at 14-15 knots (which has happened on occasion).

If you intend to tow a boat or boats, while they may be relatively little drag they will still be affected by wind and currents. I would think the potential to put in more power if you need it would be well worth it.

So I would think about going with smaller engines very carefully because once you sign the check, you can never have any more power than that no matter what happens unless you sign another really large check to re-engine the boat.

-- Edited by Marin on Wednesday 10th of November 2010 12:36:28 AM

 

[Codger2]

Marin wrote:"You can always run a larger engine at a lower power setting but you can NEVER get more power out of a small engine if you need it........there's no such thing as too much power in boats or planes (or cars for that matter). Obviously that's dependent on the hull being able to use the extra power.

There is a fellow on this forum named Carey. He also operates at speed in rough water where his hull does a lot better at 14 knots or so than at 8 or 9." ______________________________________________________________

I only highlighted part of Marin's post but I agree with everything he said. Not to mention that when you decide to sell, I guarantee buyers will buy the boat with the bigger engine for all of the reasons given above.

I find it interesting that some of TF posters go to extreme lengths to save a gallon /hr on their boats. When they get back to the marina , they glance at the fuel gage and take great pride on how little fuel they've used, before getting in their Hummers or Suburbans for the drive home. (??????)* Where do you use the most fuel over the course of a year? Your car or your boat? The obvious answer is your car! (And that is why I drive a Prius.

 

[Peter B]

Surely this 'underloading' thing is another one of these traditional wisdoms which is totally over-played? We don't drive our cars around at near wide open throttle, and the life of a car engine well serviced is pretty impressive. My much-loved land vehicle, a 1990 Celica GT4, is on 250,000 kms now, (yes another oldie but goodie - most of my things are, and I still am in awe of this car), and still uses not enough oil between services to need adding any. Running at the optimum temperature is surely the thing, and that is governed more by the thermostat than the revs or load. Ok, one maybe can't totally compare a marine diesel with land used petrol driven vehicle, but the physics are not that different. They both love a burst now and then to 'blow out the cobwebs', (and my, how good that feels), but most of the time, if at proper operating temp, they love not breathing too hard in my view.

 

[Mappy]

Superdiver

By the looks of your avatar you have a Californian 34 and I assume the T6.354 engines. Can you tell me what rpm you would be running to get 7 -8 knots trough the water? This will be the rpm that I would need to run to tow the sail boat(s).

If you have a guess at fuel consumption at that rpm that would be helpful as well.

I am slowly coming around to the turbo idea but still have concerns about the effects of 5 - 8 hr runs at a low rpm.

Thanks

 

[SD2022]

We run around 5 gph, same turbo diesel!

 

[Mappy]

Thanks Superdiver

Thanks for the info.

So what speeds would you be getting at 1800 and 1900?

Roger

 

[markpierce]

It's hard to imagine a planing boat without too much power.* On the other hand, if towing displacement*sailboats, I wouldn't dare go faster than displacement speed.

My future trawler has twice as much horsepower than needed*even though*I opted out of*the optional*turbo-charged engine.

 

[Mappy]

I have made my decision and gone with the normally aspirated engines. In fact the 4.236 Perkins which are only 85 hp each. I have only about 8 hours on the boat since buying it but I am happy with the decision.

Thanks everyone for the input.

Roger

 

[Per]

the californian was designed with the GB as a model, but flatter bottom towards the stern and larger engines to make it possible for higher speeds.

to me that is one of the highlights of the californians. we have the 38'.
we have the twin turbo 260hp, i generally run them between 1500 and 2200 rpm.
the boat pretty much does 5kts in idle (600 rpm), 10kts at 1500 rpm.

 

[FlyWright]

Mappy, Congrats on your new tug-boat. Now it's time for a new avatar. Got some pics to post?