Blueprinting hull and making it smooth and straight

**WaterZebra** · 03-27-2023, 10:21 AM

Originally Posted by Jim Speros

Some nice work people have shared. If all your doing is repairing nicks and void pops white Marine tex works well. Easy to use and can be buffed. May not make a perfect match of color but works well.

The faster the boat goes the more important a true bottom matters. 60 mph you may not notice much of an improvement. At 100 small improvements can be noticeable.

Old stock outboarders trick...............use black rattle can primer and wet sand with 400 grit. Fine lines of the 400 grit make the surface really slick. Makes touch up repairs a snap.

**OnPad** · 03-27-2023, 11:49 AM

Originally Posted by rgsauger

When folks talk about straight bottoms and square crisp edges, how much difference on handling does it make before and after?

It makes a big difference.
My Bullet basser was so beat up, it wanted to blow out and hook, in the low 60's. I tuned it up a bit with pc-7 epoxy, and it made a world of difference.

**LakeFever** · 03-27-2023, 12:24 PM

I forgot about marine tex. I used that to repair the chips on my first stream. Worked great

**OnPad** · 03-27-2023, 12:30 PM

Someone spread marine tex on the bottom of my boat, it looked like a birthday cake. It definitely ain't fallen off.

**rgsauger** · 03-27-2023, 10:17 PM

Originally Posted by OnPad

It makes a big difference.
My Bullet basser was so beat up, it wanted to blow out and hook, in the low 60's. I tuned it up a bit with pc-7 epoxy, and it made a world of difference.

well that’s me. Dang thing occasionally gets a mind of her own and hooks to port. I have had it be aggressive and I have had it just make a slow forceful hook to port. Both of them suck and scare the chit out of me! I had it happen again a few weeks back just when I thought I was over it.

I shaved 54 lbs off of starboard side and 12 or so off of port. Plus I’m down 30lbs so 85 off of starboard. 100 total. And now I have to learn to drive the sumbitch all over again. Extreeeeeeeeemly trim sensitive.

**donmac** · 04-05-2023, 06:56 AM

straight and balanced is important, smooth not so much, you don't see many smooth golf balls!

**powerabout** · 04-05-2023, 07:01 AM

Originally Posted by donmac

straight and balanced is important, smooth not so much, you don't see many smooth golf balls!

golf balls are spinning, does the SR71 have a golf ball finish?

**donmac** · 04-05-2023, 07:04 AM

doesn't need to spin creates it's own lift!

**powerabout** · 04-05-2023, 07:40 AM

Originally Posted by donmac

doesn't need to spin creates it's own lift!

yes hence why nothing that goes fast has a surface like a golf ball

**donmac** · 04-05-2023, 08:04 AM

Please do some investigation before posting your personal thoughts and possibly misleading people! I wish Owen Boris RIP was still with us,sure he could shed some light on the conversation being an Avro|Arrow engineer and speed record holder with his Alison,you might listen! I was cutting teeth rigging in those stables and examining setups when he was setting records!

if smooth is fast, why put a step in a hull, to introduce air to break surface tension, dimples do the same for a lighter boat!

**LakeFever** · 04-05-2023, 03:20 PM

The consensus seems to be 400 grit texture for the pad and primer or raw aluminum for the lower unit. Have yet to see anyone run or suggest a golf ball finish but I did know a guy who built a race engine with dimples in the intake ports. Never did see how that worked out for him but I always remembered seeing it. Water skis ( at least the ones I like ) have a slightly textured bottom finish. Too slick and shiny I did not like the feel. Ironically I felt the rougher finishes had better bite, maybe its a hydro wedge thing, dunno, beyond my pay grade. Most of the AVRO engineers went to work at NASA after AVRO folded shop.

**Jim Speros** · 04-05-2023, 05:13 PM

I am with Lake fever on this. I won't argue whether some allison may have had dimples on its bottom or not but, I won't believe for a second the alleged dimples were on the pad and/or made it faster. The way air moves around something is entirely different from the way water acts.
I've seen a lot of race boats in the last few decades. I looked closely at the winning ones. I don't ever recall seeing a golf ball dimple on any one any where.

**donmac** · 04-05-2023, 08:18 PM

more than one allison had it! you've probablly never seen a 3 ft. long gearcase but doesn't mean they didn't exist or didn't work! I don't think we have many mach speed aircraft engineers chasing boat speed records these days is likely were really only chasing "smooth"
pretty sure the first guy to put a lip on the pad and saw improvement was told he was full of **** as well!

**Jim Speros** · 04-05-2023, 08:47 PM

Some people have bottomless checkbooks funding their go fast boats. If its out there and worthy it would be on display somewhere.

**LakeFever** · 04-06-2023, 06:20 AM

Id like to see results on the golf ball dimples. Plus this would be hard to achieve in real application. Can you imagine trying to pull a dimpled hull out of a mold without wrecking it? There is the option of some sort of top coat. I havent seen anything like this anywhere, ever. So maybe your onto something but i’ll be leaving mine at 400grit. Post up the results before after would be interesting to see. I doubt youd realize 1mph difference but i sure would love to be proven wrong