View Full Version : Purpose of this fiberglass extrusion in bilge

12-19-2011, 04:00 PM
This is a 93 ProStar. The picture is in the rear of the bilge towards the rudder.

What is the purpose of the fiberglass hump that is part of the interior fiberglass pan (circled in RED)?

As you may see (circled in GREEN) there is a crack along the corner of this fiberglass block that needs to be repaired.

I had a leak in an exhaust muffler and I pulled the muffler to add a fiberglass a patch over the hole. Before replacing the repaired muffler, I was cleaning the bilge when I noticed the crack in the fiberglass pan.


The fiberglass patch worked really well. I used West System Epoxy (105/206) that I had left over from a project several years ago.

One thing always leads to another.

SPSinclair 190
12-19-2011, 09:36 PM
I have a 93 prostar as well but dont have this in my boat. I cant wait to see where this goes!

12-20-2011, 12:50 AM
The only thing that I can think of is so that you can have the larger prop. Do you have a slot transmission?

12-20-2011, 01:24 AM
Do you have a powerslot? I wonder if that piece helps reduce the vibration from the larger prop?

12-20-2011, 01:42 AM
standard 1:1 BW trans; 1 in shaft and 13x13prop.

Even if it was a powerslot with a larger prop, the prop fins would be closer to rudder. This box is right behind the prop strut. This box is at the end of the interior fiberglass tub. Between this box and the transom the interior of the hull is exposed. The rudder bolts through to the hull with no interior liner to interfere.

12-20-2011, 07:51 AM
My 94 205 has that. My guess is to add support / spread out the load from the strut. Mine was unfortunately cracked differently from a stump visit long ago... It was fixed at that time. I would absolutely do something about it.

It is odd the other fellow w/ same hull does not have it though.

12-20-2011, 08:58 AM
My 94 205 doesn't have it either

Table Rocker
12-20-2011, 09:24 AM
You can see it in my '96 205.

12-20-2011, 11:27 AM
My 93 prostar has it. I believe it is extra support for the prop wash/rudder area. Think about the pressure applied to the hull from the rudder.

12-20-2011, 11:29 AM
I looked last night and my 95 has it also

12-20-2011, 11:44 AM
How long is your skiing season and do you ever get out of a wet suit?I looked last night and my 95 has it also

12-20-2011, 11:53 AM

we ski generally from mid april to beg of oct.

wet suit in the beginning of the year and a heater shirt at the end

12-20-2011, 11:57 AM
Cool-------yall are tough.

12-20-2011, 12:02 PM
Where I live is fairly warm, bottom of a valley, 1000' above sea level, surrounded by 1 huge lake and 2 smaller lakes and a puddle

01-10-2012, 09:30 AM
Oops I lied I do have it on my 94 205

01-10-2012, 10:11 AM
Isnt It A Solid Bottom For The Middle Of The Gas Tank To Sit On?

01-10-2012, 10:24 AM
My '88 had it!. It also squeezed the bilge blower air duct.

Table Rocker
01-10-2012, 10:32 AM
Isnt It A Solid Bottom For The Middle Of The Gas Tank To Sit On?
It's not that tall. The steering goes over the top of it.

01-10-2012, 10:32 AM
not for gas tank. It is below floor line and the rudder control cable is above it. Nothing is resting on it.

I am in China right now. I will post some new pics this weekend after I get home. I have repaired crack with new fiberglass/resin.

Still not really sure of it"s use. I think it's only purpose is to give some structure to the inner liner as it gets mated to the hull. After the liner has been bonded to the hull, I don't think it has a purpose.

01-10-2012, 10:35 AM
My 92 had it.