1972 fantasy 17' tri-hull bowrider won't plane out

[bronc76]

This is my first boat and when I took it out it would only get 10mph verified by gps. It rides bow high and won't plane out. I'm not sure what the correct prop for this boat is but I believe the previous owner just used what he could find. OK particulars: boat has an aq130c volvo penta 130hp with a 270 out drive 2:15-1 it is 17ft not sure of weight. The current prop is a 14.8"x17pitch. I am only getting 2900 rpm at wot. Average weight of gear and passengers 6 to 700 pounds. I have done a compression check on motor all 4 cylinders are within about 3psi of each other and holding on a leak down test. I have checked the exhaust bellows to make sure they are unrestricted. Engine revs free and sounds good in or out of water in neutral. I was told I was over propped and should be running like a 14"x 13pitch prop. I mainly use the boat for lake fishing and my kids would like to be able to put the ocasional tube behind it if it will ever pull a tube. I'm not concerned with a really high top speed but 10mph is a bit too slow. I dont have trim that I can adjust while underway but it does have 2 trim plates that are set even with the hull on stern of boat. The engine has approx 100hrs on it since getting rebuilt according to previous owner. I have tried putting the weight in front didnt help. I moved the pin position that locks outdrive position to the futhest hole from stern of boat which the manuel I have said would help plane out and bring the bow down. Didn't work either. The current prop is a little beat up but Eric at Maverick Marine in Van Nuys, CA said it would vibrate a little but wasn't so bad it would keep it from planing. Please help if you can. I'm running out of ideas. Oh and current prop is aluminum and made by solas.

 

[Robbabob]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

Lots of good information. Add a little more from this link and we'll be ahead of the game http://forums.iboats.com/showthread.php?t=287818

Sounds like you have fixed trim; set to a place and leave it for your trip! placing it farthest from hull/transom will cause it to plan out longer. Keeping it fully into the transom will plane quicker. However, I'm not sure I've heard of an I/O having fixed trim. You mention out drive so it's not an outboard. I'm a bit confused, so please respond with more information.

Thanks and good luck!

 

[steelespike]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

First thing ,with an older boat, that I think of is water absorbed in the hull or foam under the floor.
Then are all plug wires hooked up?Are they on the right plugs.Is the carb opening all the way?Is the motor timed right and advancing as it should.I think the 17 would be close to normal.
Don't assume any of these things are right because of the recent rebuild.
Your rpm is really low because the boat isn't getting over the hump.

 

[bridweezul]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

can you provide a pic of the alf section? ty

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

It is an inboard outboard. 2.0l volvo penta inline 4cyl aq130c with a 270 outdrive. It has dual single barrel solex carbs on it. I checked the throttle to make sure it was opening all the way and it is. Plugs brand new, wires brand new and wires check out with ohm meter. new points adjusted correctly point gap and dwell. The hull is in really good shape and after 8 hrs in the water the bilge has approx 2 cups of water in it barely enough for pump to even pick up that leads me to believe water logging of foam shouldnt be the case. Will check timing advance again today to confirm but was working when last checked and was still having problem.

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

As for the provided link above I answered all those questions except for weight in my initial paragraph. I don't know the weight of the boat and have had no luck trying to find that out. I will post pic of alf section. I did find out engine max rpm, it is 5100. I'm not sure how to post pic. It wants a url and my pics are just on my computer. If someone can tell me how to do this I will post pics. Thank you

 

[steelespike]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

You need to use a host site.I haven't been able to figure it out myself.

 

[Stratos 185XLS]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

put pics on photobucket.com, copy the image url and paste in your post.

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

OK I think I kinda figured it out as far as how to post pics. I have a website for my 1976 Bronco and just posted boat pics in photo albums. There is an album named 1972 Fantasy Bowrider click on that and has like 4 pics. One of which shows the drive and all.

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

http://s1106.photobucket.com/albums/h362/bronc1976/ Here are the pic I hope now on photobucket.

 

[steelespike]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

A 17ft boat with 130 hp should plane easily and approach 40 mph.
Your 17" prop seems reasonable with 3 sizes below 15",13,11 and 2 sizes above 19,21..
on the iboats Volvo 270 short hub prop chart.

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

Thanks alot for the reply. I just can't seem to figure this out. How do you check for a water logged hull? If my hull was waterlogged wouldnt I get alot of water running back into bilge? I have done every imaginable test on the motor. Comp. test, leak down test, put vacume guage on carbs , checked plugs, plug wires, set timing and dwell, checked coil. Engine is in great shape all cyl are within 3psi of each other. I sent my 17p x 14.8" prop in to be repaired. I requested to have it repitched to a 15 if they could but not sure if they can do that to an aluminum prop. I will talk to prop guy when he picks props up from local boat store on Monday. When they repair a prop if I wanted a 14" diam rather than 14.8" can they cut it down to fix the nicks rather than adding material?

 

[Wingnutt]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

The best way to check for waterlogged foam is to weigh the boat. Then check that weight against the known dry weight. Add to the dry weight for weight of fuel and gear and look at the difference. Don't be surprised to see an extra 500-800 lbs of weight or more if the foam is soaked.

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

Not sure how exactly to weigh the boat unless maybe local truck scales would allow it. When at wot right now the boat is bow high would think the boat would set heavy in the water if water logged like kinda level and deep in water. I will try to get it weighed this week. Finding the dry weight of a boat I cant find any specs on may be another story. If I cant find that I wont know if its heavy. I have a single axle trailer it would be on to go to scales how do I know what to subtract for trailer weight?

 

[steelespike]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

A 77 17ft Fantasy I/O is about 2500 lbs.
If the boat isn't on the trailer weigh the trailer first,otherwise weigh afterwords.
Usually a scrap yard has a scale also the town dump/recycling site may have a scale.
Maybe one carb is lean ;perhaps you could carefully squirt same gas into the carbs one at a time or
Just tickle the choke(s).

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

Well I do know there is a scale at my recycling center but that unfortunately is not close to any lake that boat could be on for me to weigh the trailer. We tested tuned and sinked both carbs. Motor sounds fantastic. Idles perfect and goes from idle to redline very quickly and right back down to idle without a miss or any bad manners. We checked timing and dwell again did find timing about 4deg retarded from where it should be and fixed that. Dwell was well within parameters given in manual. I'm bidding on a prop that came off a glasstron I believe of roughly the same year same size with same running gear its a 14"x13pitch. Maybe that will make the difference because water logging and engine performance aren't looking like the problem at this point.

 

[steelespike]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

While the 13 may solve your problem a 13 is darn close to what you would use to push a pontoon or other really heavy or hard to push boat.
Hope it gets you there.
I wonder if someone missed the cam timing marks.We had a car that they missed the cam timing
it acted normal except that it wouldn't start on a cold day 30 or less.
The dealer was honest enough to admit it was their fault and no charge.

 

[codertimt]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

Don't have any other advice than was already given, but I just wanted to reiterate the advice on motor position since although mentioned a couple times, I don't see anything about it being changed. You definitely want the motor down as far as it can go. Moving the pin to the further out position and thus tilting the motor up is going to cause the stern to dig and the bow to raise and not plane...exactly what you describe in your original post. Make sure it's down as far as it can go...

I would also go ahead and weigh it on the trailer just to get a ballpark. If it's some crazy high weight you know there is a definite problem...if it's somewhere in the 3000s your probably okay. Not definitive, but more data is always a good thing.

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

Thanks alot for the advice all is appreciated. I will weigh the boat and trailer as soon as I take it out again. My Seloc manual says to put the pin in the #3 position if bow is high and wont plane out. The #3 hole is the furthest from the transom. Your saying I should be in the #1 position, #2 being kinda neautral. So drive should be all the way closest to transom? I will move pin to #1. Thanks

 

[bronc76]

Re: 1972 fantasy 17' tri-hull bowrider won't plane out

Update- Bought a prop off of ebay, its a 14" volvo penta prop not sure of pitch but its way way less than my 17p. Boat came right up onto plane and reached 25mph (on gps) with 5 people in boat. I had adjusted the manual trim tabs all the way down but I think it will plane now with them even with the hull and will probably pick up another 5mph or so as they were dragging in water causing drag. My rpms were about 4600 which i think is good considering 5000rpm is max. I'm very happy with performance now and small tweaks here and there will improve performance more. Thanks everybody for the help.