User Tag List
Thanks: 0
Likes: 0
Results 16 to 30 of 63
Thread: Tunnel hull hydroplane
-
11-10-2012, 11:17 PM #16Junior Member
- Join Date
- Nov 2012
- Location
- Milwaukee, WI
- Posts
- 14
- Thanks (Given)
- 0
- Thanks (Received)
- 1
- Likes (Given)
- 0
- Likes (Received)
- 0
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
I thought it would run a lot faster than that, seeing as the boat only weighs a couple hundred pounds and the motor is under 300.
Why do you suggest a low pitch prop? I've done a little reading online about different props and I was under the impression that a lower pitch is better for pulling power (heavier boats), and a high pitch prop (23 or so) is good for lightweight boats and gives you a higher top speed.
Is it something to do with the shape or design of the boat that makes it different for tunnels?
Either way, I may take your advice on getting a bigger motor. The original owner supposedly had a 125hp on it, so maybe I'll push it a little and try to find a 150 eventually. First I need to get it sealed and painted though.
Another thing I noticed on the boat is that there are steel cables coming from the steering wheel shaft and running back through pulleys. Do you think I would be able to eliminate those and just use the standard steering cable that's on the Merc?
I looked up some pictures of LeeCraft and Molinari tunnels and my boat definitely looks more like the Molinari's but not identical.
-
11-10-2012, 11:35 PM #175000 RPM
- Join Date
- Apr 2001
- Location
- Alabama
- Posts
- 897
- Thanks (Given)
- 28
- Thanks (Received)
- 29
- Likes (Given)
- 58
- Likes (Received)
- 81
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
That looks a lot like a Pugh tunnel to me. I owned one very similar, it had a sst100 which is an omc v4. The engine made about 158 horsepower and ran 98.6 on gps. I still own a pugh hydro and it looks like your boat from the capsule nose to the transom
-
11-11-2012, 06:07 AM #18
I thing you could be in the 60's with that setup if the engine has good compression. A 3 blade cleaver 20" pitch is typical for that power. Keep that steering, it's perfect for a small cats. But first I'd put a nose cone / low water pickup. More importantly get some seat time with this combo, full tunnel cats can bite hard.
Last edited by FrenchPhil; 11-11-2012 at 06:09 AM.
ARGO Cat 18'
Mercury 2.4EFI/CLE
------------------------------------
If it's not a cat it's a.............dog ?
-
11-11-2012, 08:36 AM #19Scream And Fly VIP
- Join Date
- Sep 2002
- Location
- Alabama
- Posts
- 705
- Thanks (Given)
- 0
- Thanks (Received)
- 0
- Likes (Given)
- 0
- Likes (Received)
- 1
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
A tunnel works on a combination of hydro and aero dynamics. At a certain speed based on a particular boat's design it begins to trap air, essentially lightening the boat to over simplify the description. Anything under this transistional speed and the boat is just planing on the surface and may actually have more drag than a V Bottom. The air entrapment is why a tunnel is faster than other designs, all other things being equal. I dont think you have enough power to make the tunnel work effectively as big as the boat is. Again, the old 950s probably put out an actual net horsepower somewhere in the 70's. The 850XS of that era on a smaller boat with a better gearcase that could be run much higher only ran 70's in race trim and it probably had a horsepower advantage over the earlier 950. The reason for the recommendation of a lower pitch prop is that I dont think you could turn a higher pitch. I could be wrong, but dont think you would ever get a 23 as was mentioned into a safe RPM range with that engine. The gear ratio of the lower will enter into the consideration and I dont remember the ratio in a 950 but some of the early 70s engines had 1.78:1 rather than 2:1 which the mostly all went to in 1972. Phil and I have differing opinions on the speed potential with that engine. I don't see any likelyhood of 60's. You should keep the cable/pulley steering. It's period correct for that boat and the most trouble free option. It also is the most precise for control. The only downside is you will have to fabricate or find nostalgic steering bars to bolt on the engine. A common practice back then was a pair of steel ears, which could be made thinner than aluminum that bolted on under the rear 3 powerhead studs on each side and then a steering bar bolting to them.
bama hama
-
11-11-2012, 09:31 AM #20
The sponsons, decks and cowls all suggest late 1970s Molinari. That 950 is not really the right engine for the boat but with a light driver, it could work. As someone suggested, a 1500xs would be the right engine as it appears to be a Sport J boat. Great find, nice to see it come out of the woodwork. Hopefully you'll restore it anbd bring it to some APBA/OPC Vintage events in 2013.
MercNuts gave you the best advice re: steering and setup. Keep asking questions and pushing forward, you'll get all the help you need and want here! Just gotta filter through to what's right for you and your boat.
John Tiger
-
11-11-2012, 09:55 AM #21
Neat boat- looks like a Lee Craft- mid 80's-but I don't know if they ever made them wood? -so being wood and the design it looks like a bit molinari like or copy/splash -is there any serial number on the back transom???
-Johns right- get that restored and come out with us in 2013 to vintage events- TedLast edited by shadowcat; 11-11-2012 at 10:12 AM.
-
11-11-2012, 11:38 AM #225000 RPM
- Join Date
- Nov 2008
- Location
- Gainesville,GA
- Posts
- 171
- Thanks (Given)
- 0
- Thanks (Received)
- 8
- Likes (Given)
- 26
- Likes (Received)
- 33
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
-
11-11-2012, 11:45 AM #23
im sure you could find a super speedmaster for it , they pop up for sale on here , that would be the way to go ...
SEEBOLD CHAMPBOAT MERCURY S3000
-
11-11-2012, 01:39 PM #24
Problem with the SSM is propellers in the pitch range that he would need for that motor. They are nearly non exsistant. A standard lower unit with a cone set to the right height will run real well. Now if he had a 1500 on it and was an experianced pilot well.... 'nother story.
Bruster's Mercury solid motor mounts, details here:
http://www.powercatboat.com/Bruster/Bruster.htmlI'm been living in fast forward, now I need to rewind real slow....
-
11-11-2012, 01:50 PM #25
You will get a lot of info on this boat on boatracingfacts dot com
It is a tunnel hull, or also referred to as a tunnel boat...not a hydroplane. A hydroplane would have a large, flat bottom with shallow sponsons in front.Last edited by rev.ronnie; 11-12-2012 at 12:36 PM.
The Reverend, (Cedar Machine Service on Facebook)
1989 HST 2.5 260 Merc Offshore
1991 Vaserette YT 200 Mercury
1988 Venus XT 200 Yamaha
1983 Viper II Merc 90
1977 Viper
Mini GT tunnel, 25 Merc
"African Queen" pontoon 25 Merc
Aluma fishin tub, 20 motors to choose from!
GUESS WHAT?...I gotta fever,...and the only prescription...IS MORE COWBELL!!
-
11-11-2012, 07:20 PM #26Junior Member
- Join Date
- Nov 2012
- Location
- Milwaukee, WI
- Posts
- 14
- Thanks (Given)
- 0
- Thanks (Received)
- 1
- Likes (Given)
- 0
- Likes (Received)
- 0
- Mentioned
- 0 Post(s)
- Tagged
- 0 Thread(s)
After seeing that picture aquanaut posted, I'd say it's definitely a Molinari, possibly even the same year. I looked all over for a serial number but couldn't find anything.
I think I'll try the 950 on it for a couple runs and see how much bigger I want to go after I get a feel for it. I have a long way to go before it even touches water though. Getting all the old paint off is going to take longer than I thought, but hopefully I'll be able to bring it out to some events come springtime.
Here's some more pictures of the boat and motor. There's a picture of a cable/bracket that was sitting inside the back of the boat, anybody know what it's for?
-
11-11-2012, 08:53 PM #27
-my quick guess- throttle cable- foot throttle maybe?????
-
11-11-2012, 09:18 PM #28
the back end of the boat does not look like a molinari boat
-
11-11-2012, 10:23 PM #29
I don't think I ever saw a Molinari here in the states with a deck like that and with no transom setback. But, I could be wrong. There may be one way to tell if it is a Molinari. Or a copy of one. Look under the decks from inside the cockpit. Do they look like this photo? If it is a Molinari they will. The curved out portions in the rib between stringers are how the carpenters built these boats.
Mark N
"I'ma motorboatin' sonuvabitch!"
-
11-12-2012, 01:57 AM #30
Cool boat Should be fun,
Like Parker said you need more power a short mid and SSM.
This is the one i run on my 15ft tunnel.
DaleLast edited by 25ss; 11-12-2012 at 02:10 AM.