7.9,s with inboards
Moderators: Tim Bosma, Tom Elsen
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bob williams
- Posts: 3
- Joined: Fri Feb 07, 2003 5:24 pm
7.9,s with inboards
Are there any specific different recommendations for inboards concerning mast tuning,setup or sail trim to increase boat performance? Thanks Bob Wi.lliams #497
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Jim
inboard performance
With a little more weight (at least for mine) and a little more drag, it's important to go foot off a little more than the outboards and go for power and speed. Tune the rig accordingly.
Jim
Jim
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fleck
- Minister of propaganda and lies
- Posts: 180
- Joined: Thu Jan 16, 2003 11:58 am
- Location: Deltaville, VA
Bob,
I'm going to rattle off a bunch of stuff we do on Horizon 484. I hope there is something helpful...
I try to keep the weight forward on my inboard. From info on the fleet 7 website, the OB had 100 lbs of the additional ballast moved forward. I assume to offset the OB on the stern. But most OB racers put the motor below, in the center of the boat, when racing. So, with that thought, I try to keep the weight out of the back of the boat. All gear below is in the middle(trunk area) or forward. We keep absolutely nothing aft of the ladder(except the cushions). We keep no more that 2 people in the cockpit(skipper and trimmer), and downwind we put a person in front of the mast. This may or may not be the 'best' setup, but we've had some good results with it so far.
I've been told that most IB's weigh-in above the 4400 lbs class min. I would get the boat weighed and pull cushions off(if you need to) until you are at 4400. I have not done this yet, but it will be done before my next one-design race. Be sure to follow the class rules so you can get a weight certificate.
As mentioned before in Dave's post, you want to have the prop so the blades fold. Set the prop so the blades are in the 3 and 9 O'clock position, and put the engine in gear. When that is done, put a mark on the propshaft, and the stuffing box so they line up. That way, before the race, shut off the engine and put it in gear, go below and you can turn the motor by hand( use the compression release lever) to line up the marks. We can do this from the front of the engine. Quick and easy.
Consider changing the shaft seal to a dripless. It is a pain, but it is well worth the trouble, especially if you have the boat in and out of the water. I have a completely dry engine compartment.
Don't let the zinc on the shaft get nasty. Sand it smooth. I use an oval shaped zinc and cut on third of it away. That leaves me with a bullet shaped zinc. Then mount the zinc just in front of the strut. After it is on put some silicone over the screws to make flush. I use silicone so I can still get the zinc off with a screwdriver.
I tune the rig as posted for the OB's, but I always prefer to be on the loose side. I'd rather be dumping power instead of looking for some. As Jim posted, go for power and speed.
When sailing downwind, go deep. Run as deep as you can downwind( thanks go out to Brad Boston for teaching me that one). I think that with the board up, if you sail higher angles the shaft, strut and prop are exposed to the flow as the boat slips sideways. This makes sailing deep even more important on the IBs(i.e. It will hurt you more than an OB)
As a last note, be sure that all your OB friends know that you 'tow for beer'. It's also fun to make an overly exaggerated effort to 'haul' out the key from below deck so you can begin to motor in.
Hope some of this helps
I'm going to rattle off a bunch of stuff we do on Horizon 484. I hope there is something helpful...
I try to keep the weight forward on my inboard. From info on the fleet 7 website, the OB had 100 lbs of the additional ballast moved forward. I assume to offset the OB on the stern. But most OB racers put the motor below, in the center of the boat, when racing. So, with that thought, I try to keep the weight out of the back of the boat. All gear below is in the middle(trunk area) or forward. We keep absolutely nothing aft of the ladder(except the cushions). We keep no more that 2 people in the cockpit(skipper and trimmer), and downwind we put a person in front of the mast. This may or may not be the 'best' setup, but we've had some good results with it so far.
I've been told that most IB's weigh-in above the 4400 lbs class min. I would get the boat weighed and pull cushions off(if you need to) until you are at 4400. I have not done this yet, but it will be done before my next one-design race. Be sure to follow the class rules so you can get a weight certificate.
As mentioned before in Dave's post, you want to have the prop so the blades fold. Set the prop so the blades are in the 3 and 9 O'clock position, and put the engine in gear. When that is done, put a mark on the propshaft, and the stuffing box so they line up. That way, before the race, shut off the engine and put it in gear, go below and you can turn the motor by hand( use the compression release lever) to line up the marks. We can do this from the front of the engine. Quick and easy.
Consider changing the shaft seal to a dripless. It is a pain, but it is well worth the trouble, especially if you have the boat in and out of the water. I have a completely dry engine compartment.
Don't let the zinc on the shaft get nasty. Sand it smooth. I use an oval shaped zinc and cut on third of it away. That leaves me with a bullet shaped zinc. Then mount the zinc just in front of the strut. After it is on put some silicone over the screws to make flush. I use silicone so I can still get the zinc off with a screwdriver.
I tune the rig as posted for the OB's, but I always prefer to be on the loose side. I'd rather be dumping power instead of looking for some. As Jim posted, go for power and speed.
When sailing downwind, go deep. Run as deep as you can downwind( thanks go out to Brad Boston for teaching me that one). I think that with the board up, if you sail higher angles the shaft, strut and prop are exposed to the flow as the boat slips sideways. This makes sailing deep even more important on the IBs(i.e. It will hurt you more than an OB)
As a last note, be sure that all your OB friends know that you 'tow for beer'. It's also fun to make an overly exaggerated effort to 'haul' out the key from below deck so you can begin to motor in.
Hope some of this helps
Bob Fleck
Horizon 484
Horizon 484