Male Vs female hull molds

Does anyone know the advantages of a hull coming from a male mold compared to a female mold?
Bluetide

Structurally, there should not be any difference.
Aesthetically, quite a bit of difference.
If a female mold, it is usually polished and the 'plug', which is the hull, has the outer surface smooth as glass.
A male mold is where you lay the fiberglass up on top of it and will give a rough surface. When finished, it will have to have tons of sanding done to it before it can be painted

Normally, in most operations, the female mold is waxed and polished with a 'non-stick' wax called 'mold release'. Nothing will stick to it. The first step is to spray the gelcoat on the mold then spray a thin layer of chopped stranded mat fiberglass to it. Then they follow that with a hand layup of fiberglass to the desired thickness. When they pull the hull out, the finish is already shiney and very little touch-up id required.
Interesting concept when you think about it. The project starts with a paint job and then you stick the boat to the paint.
.

If the boat is a ONE off the plug will allow a core to be used that can make the hull either lighter or far stronger . or both.
It also cuts down wave noise and adds insulation , so no condensation on the hull.

Yes, there will be a few extra weeks of fairing from the male plug process , but its not hard , just tedious.

Solid glass in a mold works well, as the laminating can be done with all "Green" surfaces , so no grinding for secondary bonding.Heavy , but not a trawler problem.

The horror can be folks that attempt to instal a core in a female molded boat. The process is a problem as a proper bond can not be assured , tho a vacuum setup helps.

My first choice for light and strong would be a male plug and AIREX core.

No balsa ever!.

Tho the price of the best is almost in$ane!!

If simply purchasing a cookie , the mfg reputation will tell far more than the process used. Read Dave Pascoe.

FF

Thanks for the replies.
Just finished preping and painting my Willard 40 utility boat.
We realised the hull was from a male mold when it was time for fairing.Just a bit lumpy,decided on changing paint colour from a dark red to a light grey so less time was needed in the prep process.
Bluetide

Bluetide said:

Thanks for the replies.
Just finished preping and painting my Willard 40 utility boat.
We realised the hull was from a male mold when it was time for fairing.Just a bit lumpy,decided on changing paint colour from a dark red to a light grey so less time was needed in the prep process.
Bluetide

Click to expand...

This is confusing to me.
You have a Willard 40 Utility Boat - is it an old boat or brand new, unfinished and straight out of the mold?
Didn't think anyone used male molds anymore.
What would the paint color have to do with prep time?

Tony B,
Old boat 1988,been in storage as of 1993,very little use during that time.
The reason to go with a lighter colour was due to the fact that the darker colours show the imperfections.So with the light colour didn't have
to be so perfect in the prep.With the Red we would of added weeks in sanding,filling sanding.
Bluetide.

AHHHHHHHHHHHHHHHHHH. Now it makes sense.
For a fuel efficiency and speed point of view, you should try to do your best in the way of sanding and fairing below the waterline for many reasons. One being that every imperfection has a totally immeasurable amount of drag, however, multiply this my millions and you have millions of baby anchors. This is very important with low engine power. Also consider that every imperfection creates a home for very tiny sea creatures and that adds to the drag.
I have a sailboat and everytime I scrape the bottom, I actually can feel the difference.
BTW. since I don't know exactly what you are doing or your knowlwdge level, I will ask this question.......are you just sanding or are you using fairing compounds also?

The Eagle hull below the water line and above the water line is not faired very well. Being a slow trawler have not been to concerned below the water line and over time with sanding the hull and layer of bottom paint some what filled in and smooth.

However above the water line there has been some fairing but still not smooth. So rather than paying 10+ grand to have faired smooth, I painted the hull white semi gloss so the eye can not see the imperfections. So to fool the eye, use a light color and non gloss.

The next time we pull the hull white below the gunnels needs to be painted and will have some additional fairing done at that time, but will probalbe still use semi gloss white.