Estimated fuel consumption of the 36' Tri Cabin

[Oxblood]

Hello everyone,

As you all no doubt by now know, I recently purchased an '81 36' Tri Cabin. It has dual Chrysler 440's. I am curious as to what I might expect for fuel consumption.

I will be doing mainly fair weather coastal cruising on the protected waters between Van Isle and the Mainland, and speed is low on my list of priorities.

Also, any idea how reliable the motors are? The mechanic who insoected them said they are still strong and in good shape. They do need new exhaust manifolds, but he said other wise they are solid, with full compression on all cylinders. Are there some things to be wary of with these motors? I have never been a mopar man, so I need some schooling.

Cheers.

[Vitaliy]

Hey there

i cannot comment on how strong those engines are since my tri has something a bit bigger and newer, are those the original blocks?

im powered with twin marine power 454's, re powered new in 2009, these are the 7.4L motors

we estimated that at cruise speed around 2500 RPM at about 15-16 knots she burns approximately 26 GPH

however that number might not reflect what you have since its a different motor and different year boat and what not, but should give you a general idea

hope i helped[/code]

[prowlersfish]

Vitaliy's number sound about right . Run a little harder and burn a little more so .6-.7 mpg is about what to expect at a cruse on plane . Now if want to save and in no hurry run it about 7 knots and you could get maybe 1.5-2 mpg .

"how reliable the motors " these can be very reliable , But that depends on how the where taken care of , there currant condition , and how you take care of them . My experience is they are a great engine , We put a lot of hours on a set on a charter fishing boat . I am sure well over 4000 hours , never a issue with the engines them selves , a few alternators and risers / manifolds pumps /impellers stuff like that .

[Vitaliy]

With proper maintenance i don't see why an engine cant get 5k+ hours on it, gona have to change parts but the block itself should go out as long as you take care of it.

[Big D]

Very reliable engines/workhorses but as stated earlier, everything depends on past maintenance practices. You just bought her so my recommendation is to change all fluids now including transmissions, and regular maintenance parts like plugs, distributor caps, rotors, etc. The logic is that you will then have a benchmark/date from which to plan future maintenance on all these items otherwise you're relying on the last time the previous owner did it...never a good idea in spite of what they may have told you when you purchaced her.

[Vitaliy]

Very reliable engines/workhorses but as stated earlier, everything depends on past maintenance practices. You just bought her so my recommendation is to change all fluids now including transmissions, and regular maintenance parts like plugs, distributor caps, rotors, etc. The logic is that you will then have a benchmark/date from which to plan future maintenance on all these items otherwise you're relying on the last time the previous owner did it...never a good idea in spite of what they may have told you when you purchaced her.

DO you mean you wouldn't trust the judgement and the word of the PO? how rude? just kidding i wouldn't either, they will tell you anything to sell the thing most of the time.

[aaronbocknek]

the chrysler marine engine was a very reliable and strong engine. our tri cabin was built in 1972 and when dad sold her in 2008 the engines were still running strong with great compression all around. he replaced the risers and manifolds every 6 years without fail regardless if they needed it or not. it was just the thing he did. he had electronic ignition added and a fresh water flush once he relocated her to san diego in 1996. as for the engine maintenance on bubala 3, i was a big part of it up until i headed to college in the early 1980's and still lent a hand when i was home for thanksgiving breaks. so yeah, the chrysler engine is a good one, as long as it is maintained properly.

now, for consumption. not sure what i'm getting on my tri, but i can tell you she cruises very comfortably at 2900-3200 rpm and runs about 18 mph. i have a 4 barrel carb on both engines, and just below 3200 keeps it from opening up the 3rd and 4th barrel. you can actually 'hear' it when it kicks in too.
hope this helps you out.
aaron

[Oxblood]

Thanks for the info guys. Much appreciated. When I do cruise, I will be going the slow way, so I expect I will get good mileage out of her. The engines do need new exhaust manifolds, which I am having professionally done (I am not much of a mechanic). The mechanic I hired to inspect them before purchase said they were in good condition, and I know from friends in the boating community that he has a very good reputation.

Cannot wait until spring to get this thing out for a few days.

[Oxblood]

Oh, and to answer Vitaly's question about the engines in my Tri, yes, they are the original blocks with about 1100 hours total on them.

[Oxblood]

Well, it turns out I was mistaken when I thought the Tri Cabin I just purchased had 440's. It actually has the Chrysler 360's for combined rating of 500hp. That should actually play out well when it comes to fuel consumption, I would think.

[prowlersfish]

Maybe a little but it is what it is . The 360 also is a good engine also

[Vitaliy]

you didn't check before purchasing the boat?

[Oxblood]

I did not check the size. I did, however have a certified marine mechanic inspect and test them, and the genset. The only issue with the enmgines were the rusted out exhaust manifolds. Other than that, he gave them a clean bill of health. For some reason I thought they were 440's (must have confused them with another Trojan that I had looked at, but decided not to get surveyed because the F36 did not suit my needs).

[prowlersfish]

You have a F36 . ( both the conv and tri are F36s)

[Oxblood]

Let me refine that by saying a F36 Sportfisher. I found its layyout not quite as nice for a live aboard as the Tri Cabin.