Poor old boat can't plane!

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Brooks
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Poor old boat can't plane!

Post by Brooks »

I resurrected this thread - please pop to the last post - thanks!

I have a 1975 F32, with two 1986 318 engines. Help me solve the riddle as to why I can't exceed 12 kts using these clues below (I'm stumped).

The boat might be heavy - with the original 4KW genset, 4 fuel tanks, sofa, full fridge, etc. When do I worry about waterlogged stringers or other unknown weight gains?

Engines have the Edelbrock 1409 carbs AND new pertronix marine distributors (seem to advance just fine about 28 deg total by 3K).

Props are 15 x 17 - 1.25 inch shafts, both shafts have some surface corrosion damage visible near the packing nuts and flanges.

Bottom service keeps growth at bay monthly, but always leave notes that the props are showing corrosion AND that one shaft has visible play issues. Diver says he can deflect the shaft 1/8 to 1/4 inch by pulling on it.

When underway, my wife complains that the cabin is too loud over 2100 RPM - she's right. Pouring on more power only makes the cabin louder, but not really from the engines, and doesn't seem to make the boat any faster(!). over 2500 RPM there no chance of verbally communicating in the cabin. Engines are in sync by ear / no throbbing.

MY guess is that the props need to be reconditioned, and while out, have the cutlass bearings replaced on both struts. I have a few corrosion pits on both shafts - could they be a source of problem too? Do I need new shafts too? Ugh.

Love the boat - but I fear it will be in the shop for a while.
Brooks

PS - I'm in Long Beach CA, and we had the boat out for all three days. Each day was 80+ degrees. Crazy february weather.
Last edited by Brooks on Tue Aug 23, 2022 4:23 pm, edited 2 times in total.
jimbo36
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Re: Poor old boat can't plane!

Post by jimbo36 »

You may want to dial-up the shafts while you are at it. "shaft visible play issues"??
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prowlersfish
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Re: Poor old boat can't plane!

Post by prowlersfish »

I assume it got on plane for you at one time and no major drive line changes. It sounds like a dirty , fouled bottom / running gear issue .I have had good and bad divers . You do need a cutlass bearing for sure for shaft play .


A Haul out is in order to see were you stand .
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Cmount
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Re: Poor old boat can't plane!

Post by Cmount »

So I am no longer a proud Trojan Owner, but I still visit to see how much fun you guys are having and to educate myself.

My 77 f32 had the 350 318's in it. And while I was always jealous of the many cap's that seemed to go faster than I ever could, I know at 2500, I was still pretty much going your speed and not up on plane all that well. I needed to be at 3000 to 3100 rpms to hit 18-20 knots, and my top was only about 24 knots, and I never ran her that hard. I was running 17'x14s 4 blades, I had changed them for better out of the hole and dock handling but lost top end.

The noise in the salon was there as well, but I never really knew how bad since I was always on the bridge, but my crew/visitors did spend time traveling down there.

Have you tried to go to WOT to see what you actually get? I would do that every 3-4th trip just to make sure I could approach the 4000 rpms telling me all was ok. 10-15 seconds is all I would do...just to make sure the old girls could still hit their stride.

If you can weigh her when you hall, she should be 12-14,000lbs depending on fuel, and what else is aboard.

Hope that helps. We too loved out F32! A lot of boat for a 32 for sure.

Anyway, hope that helps a little. You need to for sure check the bottom if you are really feeling shakes and vibrations...but I think it is more about not getting her beyond the 12knts.

One last thing to check, how are the trim tabs performing? Are they working and doing their job?
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Re: Poor old boat can't plane!

Post by mikeandanne »

While you have the boat out check that prop sizing with the shop,because it seems you are over propped.....I believe that boat with 318's would have a hard time with a 17 pitch prop.......We have an f32 with 16x15 and we have 360's that have more hp than yours.....by your explanation it sounds like the engines are under too much load (read noisy).....Mike
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Re: Poor old boat can't plane!

Post by vabeach1234 »

Are your trim tabs working properly?
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Brooks
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Re: Poor old boat can't plane!

Post by Brooks »

Hi guys - revisiting this as not too much has changed. It's now a question about repowering without bankrupting us.

My 1975 Trojan F32 is a great boat - but I've always thought it was underpowered. I've been really envious of you guys hitting 20+kts, when I'm lucky to get anywhere near 13.5 kts. I was ok with it until the last time coming back from Catalina, with a following sea - if I was a little faster, we would have had a smoother crossing. And I'm just looking for 17kts - not 25(!).

Thus - I'm looking for opinions - I think my Chrysler 318s are getting tired at almost 2000 hrs each; stbd side can't reach WOT with the now 15x15 props anymore, and they're both putting out some white smoke. Shafts and cutlass bearings got replaced, and alignment is pretty good. I've replaced everything on them other than the long block. I'd like to "upgrade" from 318's to 360's as it sounds easy, keeps nearly everything, other than the flywheel, balancer, and cast aluminum oil pan. That's the only advantage I see - it looks like a cheaper path - essentially an off season DIY $7500 project.

Who's done the 318 to 360 migration - was it worth it? 225 to 250 hp, +25 ft/lbs of torque. Did you really have to change out the oil pan? Having any new engines would help my situation, and 360's should be better, but only by 10% - is it worth it, or is there a better route that won't bankrupt us and/or make the boat go up 400% in value? I'd love to see what can be done with $10K for all motors, parts, (labor is free).

Thanks for any insight!
Last edited by Brooks on Tue Aug 23, 2022 8:05 pm, edited 1 time in total.
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prowlersfish
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Re: Poor old boat can't plane!

Post by prowlersfish »

How is the bottom? how did run after the last haul out with fresh paint? Have you ever sent the props to the prop shop and had them scanned? With that said your engines could very well be tired. Fresh engines are always nice. I will check on the oil pan.
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prowlersfish
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Re: Poor old boat can't plane!

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How is the bottom? how did run after the last haul out with fresh paint? Have you ever sent the props to the prop shop and had them scanned? With that said your engines could very well be tired. Fresh engines are always nice. The 360 oil pan has baffles or a windage tray and without them there is an issue that causes power loss. This is from a good source. Loses up to 100 hp I have been told.
Boating is good for the soul
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Life is to short for a ugly boat :D
Brooks
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Location: Long Beach, CA

Re: Poor old boat can't plane!

Post by Brooks »

Thanks for the insight!

The boat was painted last winter - but it didn't help performance in any noticeable way. I've had the props redone, and even tried new michigan wheels at 14 x 15, revved higher, but seemed slower. Until a repower, I should get used to the slow lane, and probably put them back on.

Also - the original boat leveler trim tabs work fine, but even with giving enough time to recover, "tons of power", or slowly deploying them, the boat just doesn't quite get up out of it's hole. I think the biggest clue is that the wake is huge and very close to the back of the boat. Also, when the boat was out for paint, no-one mentioned that it seemed overweight.

I think I gotta do the 360s - Others suggest the GM 5.7s for lots of reasons, but I see the HP as about the same, and parts hasn't been a problem for the chryslers... yet.
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Re: Poor old boat can't plane!

Post by Moderator »

Have you done a compression test on yours?
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Re: Poor old boat can't plane!

Post by prowlersfish »

Well this has been going on for 6 years. I have to wonder if your engines have been tired that long. And that's a good possibility. So I have a lot of questions. Your boat is a 75 and you have 86 engines. Were the replacements complete or long blocks or?? Are the Transmissions 1.5 to 1 ? most had 1.5 to one but some were 1 to 1.

What was your max rpm on each engine with the 15x17?
3 or 4 blades?
Both early on and later?

When you tried the smaller props(14x15) what was your max RPM then ?
3 or 4 blades

What is your max RPM with your current 15x15? are they new or your old ones repitched?
3 or 4 blades?

Lot of questions I know.


Compression tests is not a bad idea to get an idea of the health of your engines.
Boating is good for the soul
77/78 TROJAN F36 Conv.
6BTA Cummins diesels
Life is to short for a ugly boat :D
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