Seamstresses- help with gaping armholes please

[OMGitsnotgood]

I have a couple of sleeveless tops which I love, but there is too much material around the arm holes so they gape.
Last time I had a top like this, I tried sewing a triangle down from the arms to a little way down the side seam, but that left a strange shape under the arm. (See my first ever MN diagram!) The tops are too well fitting to sew right down the side seam.
One top has very thin straps, and the other has a wide cowl neck so taking in from the shoulder doesn’t seem to be an option.
I really love both tops but am not wearing them because of the gape.
Is there any hope?

I’m not sure where the gape is but when I have had this problem I have solved it by taking a dart from half way down the armhole towards the bust.

The gape is at the bottom of the armhole The dotted line on my diagram is where I've taken one in before, guess that is a dart (not really a sewer!) but it affected the shape.

What you need is an armscye adjustment.

Whether that is possible depends on the fabric and how the top has been constructed so far but ultimately you probably need a dart running from the side seam to the bust point.

If you Google armscye adjustment you will find some instructions. You will probably have to take the top completely to pieces at the side seam to do it though and if it has been overlocked with a small seam allowance remaining it might be difficult to put back together.

If you find this happens with a lot of tops and you are interested in dressmaking I highly recommend making your own clothes so you can make these kind of fit adjustments - there's a supportive mumsnet group in arts and crafts

The problem is that is too big in bust or shoulder and I am not competent to put in bust darts. I did a sewing class and the teacher helped me.

Taking the side seam in solved this

Turn it inside out and have it flat int he table and pin a triangle shape widest at the armhole narrowing down to the side seam.

I did this and my dress fitter fantastically

You have a little triangle of material which I left in case I wanted to let it out.

But be careful as I did take it in too much so try cm each side.

I think that is what you might have tried but you need to turn it inside out so the triangle is on the inside !

Yes the triangle was on the inside!

Good job! . Had an image of a weird triangle flapping around

Try a narrow thinner taper

I saw a video of someone adjusting the back centre seam and the slope of the back shoulder seam in order to fix this. Pattern adjustment like that makes sense to me when I see it done but I couldn't begin to explain it! Fixed the problem though. Youtube probably has videos on this, it'll take some research...

Thanks all

Is there any chance of a photo?

I can think of two ways one could make the arm hole smaller - one with a dart underneath as you did, and potentially one sideways, the latter is dependent on the size of the arm hole.

Alternatively, the key thing with darts is the amount of fabric you want to remove from the top of the dart vs its length. Generally, the longer and thinner the dart the better. So I would play with different length using pins or even just wide tacking stitches. As an example, I would say something 6 inches long could comfortably get rid of 1.5inches of fabric at the top (i.e. 3/4 of an each either side of the seam), maybe up to 2 inches total if you're lucky.

Thank you @Ineffable23

I think the dart I tried unsuccessfully was too short and fat, I've pinned a longer, thinner one on one of the tops and it's looking promising.

Thanks all again

Fingers crossed, I am a lazy sewer but for alterations I think it's worth tacking.