How do you figure needed depth for a grotto that people will jump off of ??

GosuPaintballer

Active member
Jul 14, 2019
39
North Carolina
I'm suppose to finalize my pool drawing this week and dig hopefully next week. I am putting in a mini cave grotto and want people to be able to jump from the top of it if they want. I'm sure lots of kids will and some adults (including myself). I'm going to tell people no diving, but want to make sure my pool depth is deep enough just in-case some teenager does not listen. The top of the Grotto will be 4 ft high from the surface of the pool. I originally have a depth of 9 feet in the plans, but i'm unsure if that will be okay? Anyone have any experience jumping off something 4 feet above the pool surface and know how deep i should build my pool? My PB is unsure and i don't know how to figure this. I've researched everything about the diving envelops for boards and plat forms but can't find anything for a height of 4 feet.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,190
Central California
Grotto hopping? Well, first you start with some bunnies... :cool:

All I can offer: I have a jumping rock about 3' high. My deep end is 7.5'. My bigger kids will sometimes touch bottom, but not at "impact speeds." No one is allowed to dive off it. 9' sounds pretty good, but I love a deep end and wish my pool was 10' just to be able to swim that deep.

On the other hand, more water means more maintenance and chemicals (and probably more construction costs), so there's always a tradeoff. It's tough enough to brush a 7.5' pool.

Have you searched for any public-ish pools near you? Maybe old ones? A school or hotel maybe that has a diving platform or diving board? Or someone with a nine or ten foot pool that'll let you jump off a step ladder? Somewhere you can test this for yourself? Measure twice and cut once!
 
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Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
7,190
Central California
Interesting docs. Do the minimum depths spec'd for a given diving board height and length take into account the extra height above the board one can achieve from the spring, and the fact that the diver will be entering hands/head first? And would GosuPaintballer be able to subtract because there's no spring action off his grotto and no head-first diving? Or should he use the diving board spec to play it safe (including accounting for that one kid that just can't follow the rules)?
 

HeyEng

Gold Supporter
Silver Supporter
Nov 7, 2018
567
Oklahoma City, OK
Good info! Our neighbor has a "mega pool" (like you would see on the TV shows) and they have a large grotto and it's 9' deep at that point. They have said that it is a good depth and wouldn't want it any deeper since that makes cleaning a little more of a chore. Here are a couple of pictures for reference as I am not sure the height from the top of the grotto to the surface. 1 (2).jpg2 (2).jpg
 
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GosuPaintballer

Active member
Jul 14, 2019
39
North Carolina
Thanks guys.... I'm thinking 9 feet of depth would probably be okay, but surely 9.5 feet deep would be plenty. Don't ya think ? A rock with no spring (unlike a diving board) and 4 ft high, i would think someone could dive into 9.5 feet and not worry about hitting the bottom ???
 

jberger

Member
Jul 9, 2017
9
Alabama
The Ansi Standard doc listed above shows the specifications you need.
I read it this way, the height of the "platform" dictates the depth of the pool. so a 50in height needs a type 3 or deeper pool.

From the doc:
5.9 Stationary diving platform(s) and diving rock(s).
Stationary diving platform(s) and diving rock(s) built on site field fabricated shall be allowed to be flush with the wall and located in the diving area of the pool.
Point A shall be in front of the wall at the platform or diving rock centerline.
Diving rocks or platforms are prohibited on Pool Type O.
5.10 Stationary diving platform(s) and diving rock(s)
5.10.1 Stationary diving platform(s) and diving rock(s) shall not be permitted on Pool Type O.
5.10.2 The maximum height of the stationary diving platform or diving rock above the waterline shall be as follows:
Pool Type I 42 in. (1.07 m)
Pool Type II 42 in. (1.07 m)
Pool Type III 50 in. (1.27 m)
Pool Type IV 60 in. (1.52 m)
Pool Type V 69 in. (1.75 m).