36" Sprint Cat SAW

[Nico Leonard]

Hi guys ! I am busy with a 36" Sprint Cat for SAW racing . We are 5600 ft above sea level . I am going to use a 29.5 mod zen in it . What cg do you suggest for such a altitude ? I have looked on different forums but can not find any thing to help me make a decision . On a F41 Stryker we run at 32-34% cg with a 30.5 Qd . Will the shorter boats cg differ from that due to the higher speed it is suppose to run by increasing it to a higher number say 37-38% ? Please help me out it seems if there is not much information regarding this available or I am not able to find it ... Thank you !

 

[GRAHAME HAINES]

Logics tells me altitude on its own should not have any effect on the COG of your hull wether it is running at sea level or 5600 ft.

What altitude will affect is the tuning of your engine. The air is thinner up there so your engine will run richer than at sea level

Contact the hull manufacturer for advice on proper CG would be my advice

 

[Gary Murcott]

Good starting point is 36 I run a 43 inch cat at 38 percent hope this helps

 

[Nico Leonard]

Thank both for your reply ! Grahame altitude and cg definitely plays a role in the performance of a boat .More with cats and F1 inboards due to the tunnel hull design . There is no way that a cat set up for SAW at say 37% at the the coast is going to run the same or at its full potential 5600 ft higher . The power your engine deliver is much more at sea level and the more power your engine put out the higher speed you achieve . That cause the hull to lift out of the water due to air that build up in front of the hull . To try and achieve the same result with the same cg at high altitude is not going to work because the hull must get some lift to free up from the water . That will not happen due to lack of power ,speed lost due to altitude gain . With research i have find out that the cat will run with a higher cg at the coast than at high elevation .

I was just curious to find out if there is other boaters playing at high altitude with cats for SAW purposes and maybe get a answer regarding the cg they use but it looks like all the speed freaks is surfer dudes as well LOL ...

 

[john v]

call bob Austin at propworks. he built the record setting 36 cat. he can get you going

 

[Nico Leonard]

John it seems that no one have experience with SAW at high altitude not with props or cg settings . . Not even the big guns ... I am on my own with this one it will be a trail and error story but I have a few big guns on my side so I will give it a go ! Thank you for your reply ,,,